ChatGPT Model Comparison: 4o vs o1 vs o3-mini vs 4.5 (2025 Guide)

Introduction

In the rapidly evolving landscape of AI language models, staying current with the latest advancements can feel like chasing a moving target. OpenAI’s ChatGPT family has expanded with several specialized models, each designed with unique capabilities and strengths. Whether you’re a developer integrating AI into your applications, a business leader exploring automation solutions, or simply an AI enthusiast, understanding the distinctions between these powerful models is crucial for leveraging their full potential.

This comprehensive ChatGPT Model comparison examines four groundbreaking models: ChatGPT 4o (the multimodal powerhouse), o1 (the deep reasoning specialist), o3-mini (the efficient problem-solver), and ChatGPT 4.5 (the conversational expert). By unpacking their architectures, benchmarks, use cases, and limitations, we’ll help you navigate the expanding ChatGPT ecosystem and identify which model best aligns with your specific needs.

Key Takeaways

ChatGPT 4o: The Multimodal Marvel

• Multimodal Integration: Native processing of text, audio, image, and video in real-time
• Performance: Scores 88.7% on MMLU benchmark, outperforming previous models
• Speed & Efficiency: 50% cost reduction compared to GPT-4 Turbo with faster response times
• Image Generation: Built-in capability with excellent text rendering and multi-turn refinement
• Ideal For: Applications requiring cross-modal interaction, visual communication, and real-time assistance

ChatGPT o1: The Deep Thinker

• Reasoning Specialist: Uses “chain of thought” processes to solve complex problems step-by-step
• Problem-Solving Power: Ranks in the 89th percentile on competitive programming (Codeforces) and solves 83% of AIME problems
• Thinking Time: Takes longer to respond but delivers more accurate results for complex tasks
• Pro Mode: Enhanced version with additional computational resources for even deeper analysis
• Ideal For: Scientific research, advanced coding, financial modeling, and legal analysis

ChatGPT o3-mini: The Efficient Reasoner

• Balanced Performance: Matches o1’s capabilities in STEM areas with faster response times
• Adjustable Reasoning: Three effort levels (low, medium, high) to balance speed and accuracy
• Accessibility: First reasoning model available on the free ChatGPT plan
• Developer-Friendly: Supports function calling, structured outputs, and search integration
• Ideal For: Coding tasks, mathematics problems, scientific analysis, and logical reasoning

ChatGPT 4.5: The Conversational Expert

• Unsupervised Learning: Largest model focused on pattern recognition rather than explicit reasoning
• Natural Interaction: Enhanced conversational abilities and emotional intelligence
• Knowledge Base: Broader knowledge with reduced hallucinations (37.1% hallucination rate)
• Context Retention: Better prompt adherence and coherence over longer interactions
• Ideal For: Content creation, writing assistance, customer-facing chatbots, and general knowledge tasks

1. Where do we begin?

The field of artificial intelligence has witnessed remarkable advancements in recent years, particularly in the domain of large language models (LLMs). OpenAI’s ChatGPT series has been at the forefront of this evolution, offering increasingly sophisticated models capable of understanding and generating human-like text. This report presents a detailed technical comparison of four specific models within the ChatGPT family: 4o, o1, o3-mini, and 4.5. These models represent distinct approaches and optimizations in LLM development, each with unique capabilities and intended applications.

This analysis will delve into their key features, performance benchmarks, underlying architectures, training data, intended use cases, strengths, weaknesses, release dates, and current availability, drawing upon official announcements, research articles, and community discussions to provide a comprehensive understanding for technical professionals and decision-makers. The information presented aims to facilitate informed choices regarding the selection and application of these advanced language models based on specific requirements and objectives.

2. ChatGPT 4o: A Comprehensive Analysis

2.1. Key Features and Capabilities:

ChatGPT 4o represents a significant leap forward as OpenAI’s first natively fully multimodal model, capable of processing and generating outputs across text, audio, image, and video modalities in real time.1 This integration allows for a more natural and intuitive interaction, mirroring human communication more closely than previous iterations.2 Notably, it offers enhanced speed and cost-efficiency compared to its predecessor, GPT-4 Turbo, potentially making advanced AI assistance more accessible.1 The model also supports over 50 languages, breaking down language barriers and facilitating global communication.1

A key advancement in ChatGPT 4o is its native image generation capability, deeply integrated into the model’s architecture.⁶ This feature excels at accurately rendering text within images, enabling visual communication for applications like street signs, menus, and invitations.⁶ The model supports multi-turn image generation, allowing users to refine images through natural conversation and ensuring consistency across multiple iterations.⁶ Furthermore, it demonstrates improved instruction following for generating images with attention to detail, capable of handling a larger number of objects (10-20) compared to other systems.⁶ ChatGPT 4o can also learn in-context from user-uploaded images, seamlessly integrating their details into the image generation process.⁶ Leveraging its knowledge base and chat context, it can transform uploaded images or use them as visual inspiration.⁶

Beyond image generation, ChatGPT 4o boasts enhanced token handling, processing up to 100,000 tokens, which is double the capacity of GPT-4 Turbo.⁵ It also retains the ability to analyze data and create charts, engage in conversations about photos, and assist with summarizing and writing tasks based on uploaded files.¹ The model integrates with Custom GPTs and the GPT Store, potentially offering access to a wide range of specialized AI applications.¹ With its improved language processing, ChatGPT 4o facilitates more nuanced and natural conversations.⁵ Its real-time voice interaction capability, with audio responses as fast as 320 milliseconds, further enhances the conversational experience.² Updates to the model in March 2025 have further enhanced its problem-solving abilities in STEM and coding, improved instruction following, and increased formatting accuracy.⁸

2.2. Performance Benchmarks and Evaluation Metrics:

ChatGPT 4o demonstrates strong performance across various benchmarks. It matches the performance of GPT-4 Turbo in English and code while showing significant improvements in non-English languages.10 Its audio Automatic Speech Recognition (ASR) performance surpasses Whisper v3, and its audio translation capabilities exceed those of models from Meta and Google.10 In visual perception, it achieves state-of-the-art results.10 The model also exhibits improved tokenization efficiency across multiple languages.10 On the Massive Multitask Language Understanding (MMLU) benchmark, ChatGPT 4o scored 88.7%, outperforming both GPT-4 and Claude 3 Opus.4 It also shows a significant lead in the MATH benchmark with a score of 76.6%.4 Additionally, it achieved scores of 53.6% on the GPQA benchmark and 90.2% on the HumanEval benchmark.4 Its vision understanding capabilities are strong, as evidenced by its performance on benchmarks like MMMU, MathVista, ChartQA, and AI2D.4 The model’s audio understanding and response generation speed are near-human, with an average response time of 320 milliseconds.4 In overall rankings, ChatGPT 4o has been placed at the top in the LMSYS leaderboard.12

2.3. Underlying Model Architecture and Training Data:

ChatGPT 4o utilizes a novel architecture that trains a single new model end-to-end across text, vision, and audio, processing all inputs and outputs through the same neural network.11 This unified approach distinguishes it from earlier models that employed separate models for each modality.2 The image generation capability is built with OpenAI’s most advanced image generator yet.6 The model undergoes aggressive post-training, contributing to its impressive visual fluency.6 ChatGPT 4o also features improved language tokenization, requiring fewer tokens for certain languages, particularly those not based on the Latin alphabet.10 The model was trained on data up to October 2023 but can access the internet to provide more current information.14 It has a context length of 128,000 tokens.14

2.4. Intended Use Cases and Target Audiences:

The intended use cases for ChatGPT 4o are extensive, leveraging its multimodal capabilities. These include useful image generation for applications like creating whiteboard sessions, comic strips, and science experiments.6 It facilitates visual communication through accurate text rendering in images and supports refining images through natural conversation in multi-turn generation.6 The model is suitable for creating photorealistic images for various purposes.6 Its applications extend to customer support, content creation, healthcare, and finance, benefiting from its enhanced responsiveness, accuracy, and multilingual support.2 ChatGPT 4o can be used for real-time voice translation, interview preparation, image analysis and recreation, coding assistance, meeting facilitation, and providing assistance to the visually impaired.15 It can also offer financial advice and enhance product images and brand assets.15 Furthermore, it can simulate conversations, analyze social media success, create infographics and posters, generate 3D objects and fonts, improve website design, create consistent characters, and serve as an educational tool.17

2.5. Strengths and Weaknesses:

ChatGPT 4o’s strengths lie in its native multimodality, enhanced speed and responsiveness, improved language support, and advanced vision capabilities.1 Its accurate text rendering in images and strong performance across various benchmarks are notable advantages.4 The near-human audio response time and reduced API cost further contribute to its appeal.2 However, it exhibits weaknesses in tasks requiring abstract reasoning, such as word manipulation, pattern recognition, analogy, and spatial reasoning.21 Understanding complex emotions and interpreting multi-speaker environments can also be challenging for the model.10

2.6. Release Date and Current Availability:

ChatGPT 4o was announced on May 13, 2024, with its image generation feature released on March 25, 2025.6 Updates to the model were released on March 27, 2025.9 It is currently available in ChatGPT for both free users (with limitations) and paid subscribers (with higher usage limits).7 The model is also accessible through the API as chatgpt-4o-latest.9

3. ChatGPT o1: A Comprehensive Analysis

3.1. Key Features and Capabilities:

The OpenAI o1 series represents a new class of language models specifically designed for enhanced reasoning and complex problem-solving.24 Unlike traditional LLMs that respond instantly, o1 models spend more time “thinking” before generating an answer, employing a “chain of thought” approach to break down complex tasks into simpler steps.26 This deliberate process, facilitated by reinforcement learning, enables o1 to try multiple approaches, recognize and correct mistakes, and ultimately arrive at more accurate and insightful responses, particularly in domains like research, strategy, coding, math, and science.25 While GPT-4o is generally recommended for most prompts, especially those involving tools and vision, the o1 series proves helpful for handling intricate, problem-solving scenarios.24 Notably, o1 models, with the exception of o1-pro, support all file uploads, and o1-pro currently supports image file uploads.24 The o1 series has also shown improved alignment with human feedback and a better ability to adhere to safety guidelines provided in the prompt.26 For users requiring even greater analytical power, o1 pro mode offers a version of the model that utilizes more computational resources to “think harder” and deliver superior results in areas such as data science, programming, and legal analysis.32

3.2. Performance Benchmarks and Evaluation Metrics:

The o1 series demonstrates exceptional performance on reasoning-intensive benchmarks. It ranks in the 89th percentile on competitive programming challenges (Codeforces) and places among the top 500 students in the US in the American Invitational Mathematics Examination (AIME) qualifier.28 Furthermore, o1 has surpassed human PhD-level accuracy on the GPQA benchmark, which tests expertise in physics, biology, and chemistry.28 Compared to GPT-4o, o1 shows significant improvements across a wide range of challenging reasoning tasks, including outperforming it in 54 out of 57 MMLU subcategories.28 The o1-preview model has also performed at a PhD level on tests in physics, chemistry, and biology, solving 83% of AIME problems, compared to GPT-4o’s 13%.26 The o1 pro mode further enhances these capabilities, achieving higher accuracy rates on AIME, Codeforces, and GPQA Diamond benchmarks compared to o1 and o1-preview.32 Its consistency is also superior, as demonstrated by the “4/4 reliability” evaluations.32

3.3. Underlying Model Architecture and Training Data:

The o1 series is trained using reinforcement learning to facilitate complex reasoning.26 A key aspect of its architecture is the implementation of a “chain of thought” process, where the model breaks down problems into smaller, more manageable steps before generating a final response.28 Through reinforcement learning, o1 learns to refine its chain of thought, recognize and correct mistakes, and adapt its problem-solving strategies.28 OpenAI utilizes a tailored dataset and a new optimization algorithm, alongside reinforcement learning, for training the o1 models.26 While specific architectural details have not been fully disclosed, the slower response times and higher usage costs compared to GPT-4o suggest a potentially larger model size or more computationally intensive reasoning processes.31 The knowledge cutoff for the o1 series is September 30, 2023, and it features a context window of 200,000 tokens.35

3.4. Intended Use Cases and Target Audiences:

The o1 series is specifically intended for users tackling complex problems that demand advanced reasoning, such as scientific researchers, financial analysts, legal professionals, and software engineers.30 Its capabilities make it well-suited for tasks like scientific research, financial modeling and forecasting, legal research and case review, and advanced coding.30 It can also be utilized for strategy ideation, educational purposes like course development and tutoring, UX design-to-code prototyping, and complex writing tasks.25 Furthermore, o1 can assist with symptom assessment, answering complex financial questions, solving logic puzzles, automating creative tasks, and next-generation problem-solving in science and technology.38

3.5. Strengths and Weaknesses:

The primary strength of the o1 series lies in its exceptional ability to perform complex reasoning tasks, particularly in science, mathematics, and coding, often outperforming GPT-4o.26 The “chain of thought” mechanism contributes to more accurate and in-depth answers.27 However, o1 models tend to have slower response times and are generally more expensive to use.26 They may also be less likely to admit when they don’t know an answer and have message limits for certain subscription tiers.25 Additionally, o1 models lack access to some advanced ChatGPT features like Memory and Voice.24

3.6. Release Date and Current Availability:

The o1-preview and o1-mini models were initially released on September 12, 2024.26 The full version of o1 became available on December 5, 2024, coinciding with the release of ChatGPT Pro, which offers access to o1 pro mode.26 In January 2025, o1 was integrated into Microsoft Copilot.26 The o1 pro API was launched in March 2025.26 Access to o1 is available to ChatGPT Plus and Team users with weekly and daily message limits, respectively, while Pro users enjoy near unlimited access.25 Enterprise and Edu customers gained access to o1 on December 5, 2024.25 It is important to note that o1-mini has been superseded by o3-mini in the model picker.27

4. ChatGPT o3-mini: A Comprehensive Analysis

4.1. Key Features and Capabilities:

ChatGPT o3-mini represents OpenAI’s latest advancement in smaller reasoning models, specifically optimized for tasks in coding, mathematics, and science.45 It delivers faster response times compared to o1-mini and can achieve accuracy levels comparable to or even exceeding o1 with higher reasoning settings.45 A key feature of o3-mini is its flexibility, offering three distinct reasoning effort levels: low, medium, and high, allowing users to balance speed and accuracy according to their specific needs.27 This model also supports crucial developer features such as function calling, Structured Outputs, and developer messages, making it suitable for production environments.45 Additionally, o3-mini integrates with search, enabling it to access up-to-date information with links to relevant web sources, although this feature is currently an early prototype.27 For the first time, a reasoning model from OpenAI is available on the free ChatGPT plan through the “Reason” option, alongside access for Plus, Team, and Pro subscribers with higher rate limits.27 Notably, o3-mini has replaced o1-mini in the model picker, signifying its role as the recommended small reasoning model within the o-series.27 Like its predecessor, o3-mini is optimized for STEM reasoning, matching o1’s performance in math, coding, and science with medium reasoning effort, while providing faster responses and more accurate results than o1-mini.27

4.2. Performance Benchmarks and Evaluation Metrics:

o3-mini demonstrates impressive performance across several benchmarks. With medium reasoning effort, it matches the performance of o1 in mathematics, coding, and science.27 Evaluations by expert testers have shown that o3-mini produces more accurate and clearer answers with stronger reasoning abilities compared to o1-mini, with testers preferring its responses 56% of the time and observing a 39% reduction in major errors.45 At the high reasoning effort level, o3-mini outperforms both o1-mini and o1 on the AIME benchmark and achieves comparable performance to o1 on the GPQA Diamond benchmark.45 It also performs better than its predecessor on the FrontierMath benchmark with high reasoning effort.45 On the Codeforces competitive programming platform, o3-mini achieves progressively higher Elo scores with increased reasoning effort, surpassing o1-mini and matching o1 with medium effort.45 It stands as OpenAI’s highest performing released model on the SWEbench-verified benchmark.45 Furthermore, o3-mini surpasses o1-high on the LiveBench Coding benchmark even at medium reasoning effort, extending its lead at high effort.45 In general knowledge evaluations, o3-mini outperforms o1-mini.45 It delivers responses 24% faster than o1-mini with medium reasoning effort, boasting an average response time of 7.7 seconds compared to 10.16 seconds.45

4.3. Underlying Model Architecture and Training Data:

o3-mini is a streamlined version of the larger OpenAI o3 model, designed for efficiency and accessibility.52 Its lightweight architecture facilitates deployment on smaller devices and in cloud environments.53 The model is specifically optimized for STEM reasoning.45 Training for o3-mini involved reinforcement learning on chain-of-thought (CoT) data.47 The o3-mini-high variant employs a more robust “simulated reasoning” approach, allowing for self-correction during the problem-solving process.54 o3-mini features a context window of 200,000 tokens and a knowledge cutoff date of September 30, 2023.35 It supports three levels of reasoning effort, each consuming a different amount of computational resources.47 Similar to other o-series models, o3-mini utilizes a “deliberative alignment” approach to ensure safe and reliable outputs.46

4.4. Intended Use Cases and Target Audiences:

The primary intended use cases for o3-mini revolve around coding, mathematics, and science tasks, making it an ideal tool for students, researchers, and developers in STEM fields.45 Its ability to handle complex tasks requiring logical reasoning also makes it suitable for broader applications.27 The model’s support for developer-friendly features like function calling and structured outputs positions it as a valuable asset for building production-ready AI applications.45 Specific use cases include solving Olympiad math problems, debugging code, diving deep into scientific concepts, problem-solving, code optimization, scientific analysis, automation of customer support, content generation requiring logical reasoning, development of virtual assistants, and accurate translations.48

4.5. Strengths and Weaknesses:

o3-mini’s strengths include its faster response times compared to o1-mini and its ability to match or exceed o1’s accuracy, particularly with higher reasoning settings.45 It is also a cost-effective option with adjustable reasoning effort levels for flexibility.27 The model supports key developer features and integrates with search for up-to-date information.27 However, o3-mini does not handle vision-based tasks and shares some limitations with the o1-series, such as the absence of Memory and Voice features.24 Its performance on general tasks is reportedly worse than GPT-4o, and the search integration is still in an early stage.27

4.6. Release Date and Current Availability:

o3-mini was previewed in December 2024 and officially released on January 31, 2025.45 It is available to ChatGPT Plus, Team, and Pro users, as well as on the Free plan with the “Reason” option.27 The model is also accessible through the Chat Completions API, Assistants API, and Batch API for select developers.45 Enterprise access was expected in February 2025.45 o3-mini has replaced o1-mini in the ChatGPT model picker.27

5. ChatGPT 4.5: A Comprehensive Analysis

5.1. Key Features and Capabilities:

ChatGPT 4.5 is presented by OpenAI as its “largest, and best model for chat, yet,” representing a significant advancement in scaling unsupervised learning.63 This approach enables the model to improve its ability to recognize patterns, draw connections, and generate creative insights without relying on explicit reasoning.63 Users report a more natural interaction experience with GPT-4.5, which boasts a broader knowledge base, enhanced creativity, and a more natural conversational style.63 OpenAI anticipates that this model will hallucinate less and provide more reliable performance across a wide range of general topics.63 GPT-4.5 supports all ChatGPT tools and API features, including function calling and image inputs.63 It can accept image inputs, generate SVG images in-line, and create images via DALL·E.63 The model also has access to up-to-date information through web search and supports all file types.63 Trained extensively on Microsoft Azure AI supercomputers, GPT-4.5 exhibits a deeper understanding of the world and improved emotional intelligence (“EQ”).64 It is more succinct and conversational than GPT-4o, offering better prompt adherence and context retention.64 While it demonstrates surprising coding skills in real-world tasks, it is noted as OpenAI’s “last model without built-in reasoning capabilities”.65

5.2. Performance Benchmarks and Evaluation Metrics:

ChatGPT 4.5 generally exhibits higher accuracy and fewer hallucinations compared to GPT-4o, with human evaluators often preferring its responses, especially in professional contexts.64 It leads in general knowledge with a 62.5% accuracy on SimpleQA and the lowest hallucination rate at 37.1% among comparable models.64 However, it tends to lag behind o3-mini in reasoning-heavy tasks like math and science.64 Interestingly, GPT-4.5 shows strong performance in real-world coding tasks on the SWE-Lancer benchmark, outperforming even o3-mini, although it underperforms in pure coding challenges.64 It achieved a 78% accuracy on the PersonQA benchmark, indicating good factual recall about individuals.69 The model also demonstrated an ability to maintain coherence over longer interactions, outperforming GPT-4o in task horizon scores.69 In evaluations of emotional intelligence and persuasion, GPT-4.5 showed promising results.69 Multilingual and multimodal performance also see moderate gains compared to GPT-4o.64

5.3. Underlying Model Architecture and Training Data:

GPT-4.5 represents a step forward in scaling unsupervised learning through advancements in pre-training and post-training techniques.63 Trained on Microsoft Azure AI supercomputers, it leverages architectural and optimization innovations, including new scalable techniques for training larger models using data derived from smaller ones.64 The model also incorporates Reinforcement Learning with Human Feedback (RLHF) to enhance its emotional intelligence and conversational abilities.65 Unlike the o-series models, GPT-4.5 does not employ chain-of-thought reasoning, instead relying on its vast training data and pattern recognition capabilities.63 While the exact parameter count is not publicly confirmed, reports suggest it could be around 12.8 trillion.73 The knowledge cutoff for GPT-4.5 is April 2024, and it features a context window of 128,000 tokens.65

5.4. Intended Use Cases and Target Audiences:

GPT-4.5 is intended for a wide range of applications, including improving writing, programming, and solving practical problems.63 Its enhanced creativity and natural conversational style make it suitable for creative and nuanced tasks, as well as for applications requiring empathy and broad general knowledge, such as writing help, coaching, brainstorming, and nuanced communication.63 It is also designed for agentic planning and execution.75 Due to its improved conversational abilities and emotional intelligence, GPT-4.5 is well-suited for customer-facing chatbots and assistants.65 Its strengths in content generation, factual accuracy, and multilingual capabilities also make it valuable for various applications.19 Other intended use cases include summarization of research papers, logical problem-solving (relying on pattern recognition), automation of business processes, generating marketing copy, and tasks requiring natural and intuitive interaction.69

5.5. Strengths and Weaknesses:

ChatGPT 4.5’s strengths include its bigger knowledge base, enhanced creativity, more natural conversational style, and improved “EQ”.63 It is expected to hallucinate less and deliver more reliable performance with a broader and deeper understanding of the world.63 The model offers better prompt adherence, enhanced context retention, and more succinct responses.64 However, its weaknesses include a lack of chain-of-thought reasoning, potentially slower speed due to its size, and the inability to produce multimodal outputs like audio or video.63 It is not ideal for complex logic or math requiring detailed step-by-step reasoning and may underperform o3-mini on most reasoning tasks and pure coding challenges.63

5.6. Release Date and Current Availability:

ChatGPT 4.5 was released as a research preview on February 27, 2025.9 It is currently available to all users on Plus, Pro, Team, Enterprise, and Edu plans worldwide through the ChatGPT interface.63 Initially, it was rolled out to Pro users, followed by Plus and Team users in the first week of March 2025, and subsequently to Enterprise and Edu users in the second week of March 2025.64 The model is also accessible via the Chat Completions API, Assistants API, and Batch API.66

6. Comparative Analysis of ChatGPT Models

The following table provides a comparative overview of ChatGPT 4o, o1, o3-mini, and 4.5 across key parameters:

7. Recommendations

This report has provided a detailed comparison of ChatGPT 4o, o1, o3-mini, and 4.5, highlighting their unique characteristics and capabilities. The analysis indicates that each model is designed with specific strengths and intended use cases in mind.

For users seeking a versatile model capable of handling a wide range of tasks, including those involving multiple modalities like audio, vision, and text, ChatGPT 4o stands out as the flagship option. Its speed, multilingual support, and decreasing API costs make it a compelling choice for various applications.

ChatGPT o1 and o3-mini, on the other hand, are specifically engineered for tasks requiring strong reasoning capabilities, particularly in STEM fields. o1 excels in complex, multi-step problem-solving, while o3-mini offers a more cost-effective and faster alternative with adjustable reasoning levels, making advanced reasoning accessible to a broader audience, including free users.

ChatGPT 4.5 focuses on enhancing the naturalness of conversations, providing a broader knowledge base, and reducing hallucinations. Its strengths lie in creative tasks, writing assistance, and general knowledge queries, making it a preferred model for users prioritizing fluent and reliable conversational AI.

The choice of which model to use ultimately depends on the specific requirements of the task. For complex reasoning in technical domains, o1 or o3-mini are recommended. For general chat, content creation, and applications benefiting from emotional intelligence, GPT-4.5 is a strong contender. For tasks requiring multimodality and real-time interaction, ChatGPT 4o is the most suitable option. As the landscape of LLMs continues to evolve, these models represent significant advancements, each pushing the boundaries of AI capabilities in distinct and valuable ways.

Frequently Asked Questions

Which ChatGPT model is best for general use?

ChatGPT 4o is the most versatile option for general-purpose applications. It handles multimodal inputs, processes information rapidly, and supports real-time interactions across text, images, audio, and video. For purely text-based general usage, ChatGPT 4.5 offers natural conversations with a broad knowledge base.

When should I use a reasoning model like o1 or o3-mini?

Choose a reasoning model when tackling complex problem-solving tasks, especially in STEM fields. The o1 model excels at multi-step reasoning for scientific research, financial modeling, and advanced coding challenges. The more efficient o3-mini is ideal when you need similar reasoning capabilities with faster response times and lower costs.

What’s the difference between o1 and o1-pro?

The o1-pro version utilizes additional computational resources to “think harder” on problems, delivering superior results for the most challenging tasks. It shows improved accuracy on benchmarks like AIME, Codeforces, and GPQA Diamond compared to standard o1, making it worth the higher cost for mission-critical applications requiring maximum precision.

Which model has the most updated knowledge?

ChatGPT 4.5 has the most recent knowledge cutoff (April 2024), followed by ChatGPT 4o (June 2024). Both o1 and o3-mini have knowledge cutoffs of September 2023. For truly current information, all models can access the internet through web search capabilities.

Can free users access any of these advanced models?

Yes, free users can access a limited version of ChatGPT 4o and can use o3-mini through the “Reason” option. However, paid subscribers (Plus, Team, Pro, Enterprise) receive higher usage limits and access to additional features like o1 and 4.5.

What are the context window sizes for each model?

Both o1 and o3-mini offer the largest context windows at 200,000 tokens, while ChatGPT 4o and 4.5 provide 128,000 tokens. These expanded context windows allow the models to process and maintain longer conversations or analyze larger documents.

Final Thoughts: Choosing the Right Tool for Your Task

The evolution of ChatGPT models represents a shift from the “one-size-fits-all” approach to specialized AI assistants optimized for specific capabilities. Rather than chasing the elusive “perfect model,” success lies in selecting the right tool for your particular needs:

• Need multimodal interaction and speed? ChatGPT 4o delivers real-time processing across text, image, audio, and video.
• Tackling complex scientific or mathematical problems? The deliberate reasoning of o1 provides unmatched accuracy.
• Working with budget constraints but need reasoning power? o3-mini offers an excellent balance of performance and efficiency.
• Prioritizing natural conversations and reduced hallucinations? ChatGPT 4.5 excels in fluent, knowledge-rich interactions.

The true power comes not from obsessing over which model is “best” in absolute terms, but from strategically leveraging these specialized tools based on your specific requirements. As AI continues to evolve, the most successful implementations will be those that thoughtfully match the right model to the right task, creating a complementary ecosystem of AI capabilities rather than relying on a single solution.

Start experimenting with these models today, and discover how their unique strengths can enhance your projects, streamline your workflows, and unlock new possibilities for innovation.

Works cited

1. What is ChatGPT-4o? – GoDaddy Blog, accessed April 1, 2025, https://www.godaddy.com/resources/skills/what-is-chatgpt-4o
2. ChatGPT-4o: Features, Benefits, and Uses Artificial Intelligence – The Flock, accessed April 1, 2025, https://www.theflock.com/content/blog-and-ebook/chatgpt-4o-features-benefits-and-uses
3. www.theflock.com, accessed April 1, 2025, https://www.theflock.com/content/blog-and-ebook/chatgpt-4o-features-benefits-and-uses#:~:text=This%20advanced%20model%20can%20seamlessly,as%20fast%20as%20320%20milliseconds.
4. GPT-4o Review (Features & Benchmarks) – TextCortex, accessed April 1, 2025, https://textcortex.com/post/gpt-4o-review
5. ChatGPT 4o Comparison: Versions 3.5, 4.0, and Beyond – Kanerika, accessed April 1, 2025, https://kanerika.com/blogs/chatgpt-4o/
6. Introducing 4o Image Generation – OpenAI, accessed April 1, 2025, https://openai.com/index/introducing-4o-image-generation/
7. OpenAI unveiled image generation for 4o – here’s everything you need to know about the ChatGPT upgrade | TechRadar, accessed April 1, 2025, https://www.techradar.com/news/live/openai-march-25-livestream-event
8. June 2024 knowledge cutoff for “4o” with ChatGPT Pro : r/OpenAI – Reddit, accessed April 1, 2025, https://www.reddit.com/r/OpenAI/comments/1iptpw5/june_2024_knowledge_cutoff_for_4o_with_chatgpt_pro/
9. Model Release Notes | OpenAI Help Center, accessed April 1, 2025, https://help.openai.com/en/articles/9624314-model-release-notes
10. DeepSeek-R1 vs ChatGPT-4o: Analyzing Performance Across Key Metrics. | by Bernard Loki “AI VISIONARY” | Feb, 2025 | Medium, accessed April 1, 2025, https://medium.com/@bernardloki/deepseek-r1-vs-chatgpt-4o-analyzing-performance-across-key-metrics-2225d078c16c
11. Hello GPT-4o – OpenAI, accessed April 1, 2025, https://openai.com/index/hello-gpt-4o/
12. GPT-4o Benchmark – Detailed Comparison with Claude & Gemini – Wielded, accessed April 1, 2025, https://wielded.com/blog/gpt-4o-benchmark-detailed-comparison-with-claude-and-gemini
13. How ChatGPT 4o Works Technically | FiorenzoComini, accessed April 1, 2025, https://fiorenzocomini.com/how-chatgpt-4o-works-technically-a-clear-explanation/
14. GPT-4o – Wikipedia, accessed April 1, 2025, https://en.wikipedia.org/wiki/GPT-4o
15. Top 10 Use Cases for GPT-4o – Addepto, accessed April 1, 2025, https://addepto.com/blog/top-10-use-cases-for-gpt-4o/
16. GPT-4o Guide: How it Works, Use Cases, Pricing, Benchmarks | DataCamp, accessed April 1, 2025, https://www.datacamp.com/blog/what-is-gpt-4o
17. 25 Incredible Use Cases for ChatGPT: Beginner’s Guide – Alexander Young, accessed April 1, 2025, https://blog.alexanderfyoung.com/chatgpt-4o-ultimate-beginners-guide/
18. 15 INSANE Use Cases With ChatGPT 4o Image Generation – YouTube, accessed April 1, 2025, https://www.youtube.com/watch?v=aCulf5PgjFQ
19. Unlocking the Power of ChatGPT 4.5: A Comprehensive Guide – AI Ranking, accessed April 1, 2025, https://www.airankingskool.com/post/unlocking-the-power-of-chatgpt-4-5
20. 9 Use cases for GPT-4o : r/ChatGPT – Reddit, accessed April 1, 2025, https://www.reddit.com/r/ChatGPT/comments/1crtfv2/9_use_cases_for_gpt4o/
21. ChatGPT-4o for business: everything you need to know – Springs, accessed April 1, 2025, https://springsapps.com/knowledge/chatgpt-4o-for-business-everything-you-need-to-know
22. GPT-4 – Wikipedia, accessed April 1, 2025, https://en.wikipedia.org/wiki/GPT-4
23. ChatGPT — Release Notes: 2025-March-27 – GPT-4o a new update – Community, accessed April 1, 2025, https://community.openai.com/t/chatgpt-release-notes-2025-march-27-gpt-4o-a-new-update/1153887
24. What is the ChatGPT model selector? – OpenAI Help Center, accessed April 1, 2025, https://help.openai.com/en/articles/7864572-what-is-the-chatgpt-model-selector
25. Using OpenAI o1 models and GPT-4o models on ChatGPT | OpenAI …, accessed April 1, 2025, https://help.openai.com/en/articles/9824965-using-openai-o1-models-and-gpt-4o-models-on-chatgpt
26. OpenAI o1 – Wikipedia, accessed April 1, 2025, https://en.wikipedia.org/wiki/OpenAI_o1
27. What is OpenAI o1 and o3-mini? + How they’re different – Zapier, accessed April 1, 2025, https://zapier.com/blog/openai-o1/
28. Learning to reason with LLMs | OpenAI, accessed April 1, 2025, https://openai.com/index/learning-to-reason-with-llms/
29. en.wikipedia.org, accessed April 1, 2025, https://en.wikipedia.org/wiki/OpenAI_o1#:~:text=A%20preview%20of%20o1%20was,users%20on%20December%205%2C%202024.
30. What is ChatGPT o1? A New Era for AI Reasoning – AI Today, accessed April 1, 2025, https://aitoday.com/artificial-intelligence/what-is-chatgpt-o1-a-new-era-for-ai-reasoning/
31. ChatGPT o1: new step into AI reasoning | by Unravel Technologies | Medium, accessed April 1, 2025, https://medium.com/@unravel-technologies/chatgpt-o1-new-step-into-ai-reasoning-aaae86d01f6e
32. Introducing ChatGPT Pro – OpenAI, accessed April 1, 2025, https://openai.com/index/introducing-chatgpt-pro/
33. o1 vs o1 Pro-GPT Models: Features, Pricing, Benchmarks, and Future Insights – Leanware, accessed April 1, 2025, https://www.leanware.co/insights/gpt-models-comparison-insights
34. Exploring the Architecture of ChatGPT-01-Preview: How ML and DL Techniques Build a Reasoning AI Model – DEV Community, accessed April 1, 2025, https://dev.to/agustin_bereciartua/exploring-the-architecture-of-chatgpt-01-preview-how-ml-and-dl-techniques-build-a-reasoning-ai-model-3fok
35. Compare models – OpenAI API, accessed April 1, 2025, https://platform.openai.com/docs/models/compare?model=o1
36. What Is OpenAI’s O1 Pro Mode? Features, ChatGPT Pro & More – DataCamp, accessed April 1, 2025, https://www.datacamp.com/blog/o1-pro-mode
37. To Those Using o1/o1 Pro, Why/What Do You Use It For? : r/ChatGPT – Reddit, accessed April 1, 2025, https://www.reddit.com/r/ChatGPT/comments/1hnynpq/to_those_using_o1o1_pro_whywhat_do_you_use_it_for/
38. Meet OpenAI o1: First ChatGPT Model with “Reasoning” Abilities – Kommunicate, accessed April 1, 2025, https://www.kommunicate.io/blog/meet-openai-o1/
39. 12 Use Cases to Use ChatGPT o1: Solve Problems, Code Faster, and more. – AI Fire, accessed April 1, 2025, https://www.aifire.co/p/12-use-cases-to-use-chatgpt-o1-solve-problems-code-faster-and-more
40. Practical uses for o1? : r/ChatGPT – Reddit, accessed April 1, 2025, https://www.reddit.com/r/ChatGPT/comments/1fk0ovq/practical_uses_for_o1/
41. What is New ChatGPT o1 and Its Features – Stockimg AI, accessed April 1, 2025, https://stockimg.ai/blog/ai-and-technology/what-is-new-gpt-o1
42. OpenAI Releases ChatGPT o1, ‘World’s Smartest Language Model” – Search Engine Journal, accessed April 1, 2025, https://www.searchenginejournal.com/openai-releases-chatgpt-o1-worlds-smartest-language-model/534597/
43. OpenAI o1 models – FAQ [ChatGPT Enterprise and Edu], accessed April 1, 2025, https://help.openai.com/en/articles/9855712-openai-o1-models-faq-chatgpt-enterprise-and-edu
44. ChatGPT Enterprise & Edu – Release Notes – OpenAI Help Center, accessed April 1, 2025, https://help.openai.com/en/articles/10128477-chatgpt-enterprise-edu-release-notes
45. OpenAI o3-mini, accessed April 1, 2025, https://openai.com/index/openai-o3-mini/
46. o3-mini in ChatGPT – FAQ – OpenAI Help Center, accessed April 1, 2025, https://help.openai.com/en/articles/10491870-o3-mini-in-chatgpt-faq
47. o3-mini Puts Reasoning in High Gear, How to Train for Computer Use, Gemini 2.0 Thinks Faster, and more… – DeepLearning.AI, accessed April 1, 2025, https://www.deeplearning.ai/the-batch/issue-287/
48. OpenAI O3-Mini: The Cost-Efficient Genius Redefining STEM AI | by Harsh Vardhan, accessed April 1, 2025, https://medium.com/@harsh.vardhan7695/openai-o3-mini-the-cost-efficient-genius-redefining-stem-ai-590706016804
49. ChatGPT o3-Mini: Everything You Need to Know – AI Tools – God of Prompt, accessed April 1, 2025, https://www.godofprompt.ai/blog/chatgpt-o3-mini
50. OpenAI o3-mini Review: Performance in Benchmarks & Evals – TextCortex, accessed April 1, 2025, https://textcortex.com/post/openai-o3-mini-review
51. OpenAI-o3-mini vs DeepSeek-R1 – Medium, accessed April 1, 2025, https://medium.com/data-science-in-your-pocket/openai-o3-mini-vs-deepseek-r1-23326fa36e4b
52. OpenAI o3 vs o3-Mini: Features, Capabilities & AI Updates 2025 – Zignuts, accessed April 1, 2025, https://www.zignuts.com/blog/openai-o3-vs-o3-mini
53. A Detailed Guide on OpenAI o3-mini – Future Skills Academy, accessed April 1, 2025, https://futureskillsacademy.com/blog/openai-o3-mini/
54. Diving Deep into ChatGPT o3-mini-high: A Leap Forward in AI Reasoning – Neuroflash, accessed April 1, 2025, https://neuroflash.com/blog/chatgpt-o3-mini-high/
55. o3-mini – Intelligence, Performance & Price Analysis, accessed April 1, 2025, https://artificialanalysis.ai/models/o3-mini
56. ChatGPT’s new free o3-mini model is mind-blowing — 5 prompts to try first | Tom’s Guide, accessed April 1, 2025, https://www.tomsguide.com/ai/chatgpts-new-free-o3-mini-model-is-mind-blowing-5-prompts-to-try-first
57. What’s new with ChatGPT’s o3-mini? | by Woyera | Feb, 2025 | Medium, accessed April 1, 2025, https://medium.com/@woyera/whats-new-with-chatgpt-s-o3-mini-70f8e08ea4e9
58. 5 o3-mini Prompts to Make Work Easier – Analytics Vidhya, accessed April 1, 2025, https://www.analyticsvidhya.com/blog/2025/02/o3-mini-prompts/
59. 10 o3-mini Prompts to Help with All Your Coding Tasks – Analytics Vidhya, accessed April 1, 2025, https://www.analyticsvidhya.com/blog/2025/02/o3-mini-coding-prompts/
60. Which ChatGPT Model is Worth Using? We’ve Got Answers – AI Tools, accessed April 1, 2025, https://www.godofprompt.ai/blog/chatgpt-model-is-worth-using
61. OpenAI o3 – Wikipedia, accessed April 1, 2025, https://en.wikipedia.org/wiki/OpenAI_o3
62. OpenAI o3 Release Date & Features: What to Expect – PromptLayer, accessed April 1, 2025, https://blog.promptlayer.com/everything-we-know-openais-o3-model/
63. GPT-4.5 in ChatGPT | OpenAI Help Center, accessed April 1, 2025, https://help.openai.com/en/articles/10658365-gpt-4-5-in-chatgpt
64. Introducing GPT-4.5 – OpenAI, accessed April 1, 2025, https://openai.com/index/introducing-gpt-4-5/
65. GPT 4.5 Released: Here Are the Benchmarks – Helicone, accessed April 1, 2025, https://www.helicone.ai/blog/gpt-4.5-benchmarks
66. ChatGPT 4.5: Features, Limitations, GPT-4o Comparison and Everything You Need To Know. – Digital Bricks, accessed April 1, 2025, https://www.digitalbricks.ai/blog-posts/chatgpt-4-5-features-limitations-gpt-4o-comparison-and-everything-you-need-to-know
67. Everything You Need to Know About ChatGPT 4.5 – Apidog, accessed April 1, 2025, https://apidog.com/blog/chatgpt-4-5/
68. ChatGPT 4.5 – What’s New? | TTMS, accessed April 1, 2025, https://ttms.com/chatgpt-4-5-whats-new-practical-examples-and-applications/
69. OpenAI GPT-4.5: What’s New and Why It Matters – Latenode, accessed April 1, 2025, https://latenode.com/blog/openai-chatgpt-4-5
70. ChatGPT 4.5: Features, Access, GPT-4o Comparison, and More – DataCamp, accessed April 1, 2025, https://www.datacamp.com/blog/gpt-4-5
71. ChatGPT 4.5’s Surprising Success in Coding with LiveBench Rankings – Medium, accessed April 1, 2025, https://medium.com/codex/chatgpt-4-5s-surprising-success-in-coding-a-deep-dive-into-livebench-rankings-e7a00dcda1a4
72. GPT 4.5 is here: Better, but not the best – Vellum AI, accessed April 1, 2025, https://www.vellum.ai/blog/gpt-4-5-is-here-heres-how-good-this-model-is
73. OpenAI’s GPT-4.5: Most Powerful AI Model Yet? – DocsBot AI, accessed April 1, 2025, https://docsbot.ai/article/openais-gpt-4-5-most-powerful-ai-model-yet
74. OpenAI’s GPT-4.5 will roll out to ChatGPT Plus subscribers over several days | Mashable, accessed April 1, 2025, https://mashable.com/article/chatgpt-4-5-release-rollout-openai-sam-altman
75. GPT-4.5 is live in the API! – Announcements – OpenAI Developer Community, accessed April 1, 2025, https://community.openai.com/t/gpt-4-5-is-live-in-the-api/1131571
76. 5 Real-World Use Cases of ChatGPT-4.5 That Save Time & Money – Latenode, accessed April 1, 2025, https://latenode.com/blog/5-real-world-use-cases-of-chatgpt-45-that-save-time-and-money
77. Everything You Need to Know About OpenAI’s GPT-4.5 – Analytics Vidhya, accessed April 1, 2025, https://www.analyticsvidhya.com/blog/2025/02/openai-gpt-4-5/
78. ChatGPT 4.5 — 5 big upgrades you need to know – Tom’s Guide, accessed April 1, 2025, https://www.tomsguide.com/ai/chatgpt/chatgpt-4-5-5-big-upgrades-you-need-to-know
79. Hands-on with ChatGPT-4.5: What Tech Leaders Need to Know – Avenue Z, accessed April 1, 2025, https://avenuez.com/blog/hands-on-with-chatgpt-4-5/
80. GPT-4.5 is Here, But is it Really an Upgrade? My Extensive Testing Suggests Otherwise… – Reddit, accessed April 1, 2025, https://www.reddit.com/r/ChatGPTPro/comments/1j55h6m/gpt45_is_here_but_is_it_really_an_upgrade_my/
81. en.wikipedia.org, accessed April 1, 2025, https://en.wikipedia.org/wiki/GPT-4.5
82. When Will ChatGPT-5 Be Released (Feb 2025 Info) – Exploding Topics, accessed April 1, 2025, https://explodingtopics.com/blog/new-chatgpt-release-date