o3
o3 is a text generation model from OpenAI released in April 2025, featuring a 200,000 token context window.
OpenAIDeep reasoning for complex analytical tasks
o3 is a large language model developed by OpenAI and released in April 2025. It belongs to OpenAI's "o" series of reasoning-focused models, which are designed to spend additional compute time working through problems before producing a response. The model supports a context window of 200,000 tokens and can generate responses up to 100,000 tokens in length. A configurable reasoning effort setting allows users to adjust how much processing the model applies to a given task.
O3 is particularly suited for tasks that benefit from extended reasoning, such as mathematics, science, coding, and multi-step logical analysis. The reasoning effort input lets developers and users tune the trade-off between response latency and depth of analysis depending on their use case. It is available as a text generation model through MindStudio without requiring separate API key management. OpenAI positions o3 as a model intended for complex, high-stakes tasks where thoroughness matters.
What o3 supports
Adjustable Reasoning Effort
A built-in "reasoning effort" selector lets users control how deeply the model thinks before responding, trading latency for analytical depth.
Large Context Window
Supports up to 200,000 tokens of input context, enabling analysis of long documents, codebases, or multi-turn conversations in a single request.
Long-Form Output
Can generate responses up to 100,000 tokens, making it suitable for producing detailed reports, extensive code, or lengthy structured content.
Mathematical Reasoning
Designed to handle multi-step mathematical and scientific problems by working through intermediate reasoning steps before arriving at an answer.
Code Generation
Capable of writing, reviewing, and debugging code across multiple programming languages, with extended reasoning applied to complex logic problems.
Multi-Step Analysis
Applies chain-of-thought style reasoning internally to break down complex analytical or logical tasks before producing a final response.
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Get Started FreeBenchmark scores
Scores represent accuracy — the percentage of questions answered correctly on each test.
| Benchmark | What it tests | Score |
|---|---|---|
| MMLU-Pro | Expert knowledge across 14 academic disciplines | 85.3% |
| GPQA Diamond | PhD-level science questions (biology, physics, chemistry) | 82.7% |
| MATH-500 | Undergraduate and competition-level math problems | 99.2% |
| AIME 2024 | American math olympiad problems | 90.3% |
| LiveCodeBench | Real-world coding tasks from recent competitions | 80.8% |
| HLE | Questions that challenge frontier models across many domains | 20.0% |
| SciCode | Scientific research coding and numerical methods | 41.0% |
Common questions about o3
What is the context window size for o3?
O3 supports a context window of 200,000 tokens, meaning it can process up to 200,000 tokens of combined input and conversation history in a single request.
What is the maximum response length o3 can produce?
O3 can generate responses up to 100,000 tokens in a single output, which is suitable for long-form documents, detailed code, or extended analytical responses.
What does the "Reasoning Effort" setting do?
The reasoning effort selector allows you to control how much internal processing o3 applies before generating a response. Higher effort generally produces more thorough answers at the cost of increased latency.
When was o3 released?
O3 was released in April 2025 by OpenAI and was added to MindStudio on April 21, 2025.
What types of tasks is o3 best suited for?
O3 is designed for tasks that benefit from extended reasoning, including mathematics, scientific analysis, complex coding problems, and multi-step logical tasks where depth of analysis is important.
Is pricing information available for o3 on MindStudio?
Published pricing details are not included in the current model metadata. You can check MindStudio's pricing page or OpenAI's official pricing documentation for the latest cost information.
What people think about o3
Community discussions around o3 have highlighted its long context comprehension and reasoning depth, with some users describing its performance on complex tasks as notably thorough. Early threads praised its multimodal and analytical capabilities shortly after its April 2025 release.
However, significant controversy emerged later, with a highly upvoted thread alleging that OpenAI was silently routing o3 requests to GPT-5, raising concerns about transparency and model identity. Users have also discussed broader trust issues with OpenAI's model deployment practices alongside interest in the o3-pro variant.
OpenAI's post-training lead leaves and joins Anthropic: he helped ship GPT-5, 5.1, 5.2, 5.3-Codex, o3 and o1 and will return to hands-on RL research at Anthropic
OpenAI are now stealth routing all o3 requests to GPT-5
WHAT!! OpenAI strikes back. o3 is pretty much perfect in long context comprehension.
OpenAI just pulled the biggest bait-and-switch in AI history and I'm done.
OpenAI announce o3-pro release today
Parameters & options
Used to give the model guidance on how many reasoning tokens it should generate before creating a response to the prompt. Low will favor speed and economical token usage, and high will favor more complete reasoning at the cost of more tokens generated and slower responses. The default value is medium, which is a balance between speed and reasoning accuracy.
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