OpenAI o3 Review: The Reasoning Frontier
OpenAI's o3 pushes reasoning to new heights with extended chain-of-thought and unmatched performance on math, science, and logic benchmarks.
The Reasoning Specialist
OpenAI o3 is not a general-purpose model—it's a reasoning specialist. Using extended chain-of-thought processing, o3 'thinks' before answering, breaking complex problems into steps and verifying its own logic. This produces dramatically better results on tasks requiring multi-step reasoning.
On the ARC-AGI benchmark, o3 scores 87.5% at high compute—shattering previous records. On competition-level mathematics (AIME 2026), o3 solves 96.7% of problems correctly, approaching human gold medalist performance.
Math & Science Performance
o3's mathematical capabilities are remarkable: it handles university-level calculus, linear algebra, and probability with high reliability. It can construct proofs, identify errors in mathematical arguments, and solve competition problems that stump GPT-5.
In science, o3 excels at physics problem-solving, chemistry reaction prediction, and biological systems analysis. Its step-by-step reasoning makes it possible to verify each stage of complex scientific calculations.
Coding with Reasoning
For algorithm design and competitive programming, o3 significantly outperforms GPT-5. It approaches problems methodically—analyzing constraints, considering edge cases, and optimizing solutions before writing code.
On Codeforces-style problems (rating 1800+), o3 solves 78% compared to GPT-5's 52%. The tradeoff: o3 is slower and more expensive, making it overkill for routine coding tasks.
Latency & Cost Tradeoffs
o3's reasoning process takes time. Average response latency is 15-45 seconds for complex problems, compared to 2-5 seconds for GPT-5. Token costs are approximately 3-5x higher than GPT-5 due to the extended reasoning chains.
For quick answers, simple queries, or conversational AI, o3 is the wrong tool. Its value emerges on hard problems where accuracy matters more than speed.
When to Use o3 vs GPT-5
Use o3 for: complex mathematical problems, scientific research, algorithm design, logic puzzles, formal proofs, and any task where step-by-step verification is valuable.
Use GPT-5 for: general conversation, creative writing, routine coding, content generation, and tasks where speed and cost matter more than maximum reasoning depth.
Verdict
o3 is the most capable reasoning model available. It's not for everyday use, but when you hit a problem that requires genuine multi-step logic, o3 delivers results no other model can match.
Compare o3's reasoning capabilities against other models on complex tasks via Vincony.com.