o3 Pro vs o3 Reasoning: which model should you choose?
We compared o3 Pro and o3 Reasoning on price, context window and 12 benchmarks. o3 Pro has the stronger average benchmark score; o3 Reasoning is cheaper on a blended 3:1 basis.
o3 Pro
o3 Pro is a frontier model from OpenAI. It offers a 400,000-token context window, costs $17.89 per million input tokens and $81.48 per million output tokens, and averages 85.8 across the index's benchmark suite.
- Input
- $17.89 / 1M
- Output
- $81.48 / 1M
- Context
- 400,000
- Avg score
- 85.8
- Open weights
- No
o3 Reasoning
o3 Reasoning is a frontier model from OpenAI. It offers a 200,000-token context window, costs $18.07 per million input tokens and $70.65 per million output tokens, and averages 85.3 across the index's benchmark suite.
- Input
- $18.07 / 1M
- Output
- $70.65 / 1M
- Context
- 200,000
- Avg score
- 85.3
- Open weights
- No
Specification comparison
| Spec | o3 Pro | o3 Reasoning | Edge |
|---|---|---|---|
| Input price / 1M | $17.89 | $18.07 | A |
| Output price / 1M | $81.48 | $70.65 | B |
| Context window | 400,000 | 200,000 | A |
| Max output | 8,192 | 16,384 | B |
| Average score | 85.8 | 85.3 | A |
| Arena Elo | 1471.9 | 1456.9 | A |
| Open weights | No | No | Tie |
Benchmark comparison
o3 Pro wins 8, o3 Reasoning wins 4, and 0 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | o3 Pro | o3 Reasoning | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 84.3 | 87.7 | 3.4 | o3 Reasoning |
| GPQA Diamond | 78.7 | 79.6 | 0.9 | o3 Reasoning |
| SWE-bench Verified | 76.9 | 74.1 | 2.8 | o3 Pro |
| HumanEval | 90.6 | 91.3 | 0.7 | o3 Reasoning |
| MATH-500 | 92.4 | 92.0 | 0.4 | o3 Pro |
| AIME 2025 | 83.5 | 80.5 | 3.0 | o3 Pro |
| LiveCodeBench | 82.4 | 82.7 | 0.3 | o3 Reasoning |
| IFEval | 90.9 | 90.6 | 0.3 | o3 Pro |
| TruthfulQA | 88.4 | 86.5 | 1.9 | o3 Pro |
| HellaSwag | 92.5 | 90.9 | 1.6 | o3 Pro |
| MMMU | 83.1 | 82.3 | 0.8 | o3 Pro |
| Arena Elo | 1471.9 | 1456.9 | 15.0 | o3 Pro |
Price analysis
On a blended 3:1 input-to-output basis, o3 Pro costs about $33.79 per million tokens and o3 Reasoning costs about $31.22. o3 Reasoning is roughly 8% cheaper than o3 Pro. At high volume, that gap compounds quickly, so price should carry real weight unless the quality difference is decisive.
o3 Pro has the larger context window at 400,000 tokens, compared with 200,000 for o3 Reasoning. That matters for long documents, large codebases and multi-step agent traces.
Verdict
Across 12 shared benchmarks, o3 Pro wins 8, o3 Reasoning wins 4, and 0 are tied. On the index average, o3 Pro leads o3 Reasoning by 0.5 points (85.8 versus 85.3).
The price picture favours o3 Reasoning. The context picture favours o3 Pro. Those two dimensions often matter more than a few benchmark points once a model is good enough for the task.
If you need a single default, start with o3 Pro for quality-sensitive work and o3 Reasoning for high-volume, well-scoped tasks. Run both on a sample of your own traffic before locking in a choice.
Choose o3 Pro if
- You want the higher average benchmark score in this index.
- You need the larger 400,000-token context window.
Choose o3 Reasoning if
- Unit cost matters and you want the cheaper blended price.
- You need the larger 16,384-token output limit.
FAQ
Is o3 Pro better than o3 Reasoning?
On the index average, o3 Pro leads o3 Reasoning by 0.5 points (85.8 versus 85.3). The better choice depends on price, context and your task. o3 Pro wins 8 benchmarks, o3 Reasoning wins 4.
Which is cheaper, o3 Pro or o3 Reasoning?
o3 Reasoning is cheaper on a blended 3:1 basis at about $31.22 per million tokens, versus $33.79 for o3 Pro.
Which has the larger context window?
o3 Pro has the larger context window at 400,000 tokens. o3 Reasoning has 200,000 tokens.
Are these models open weights?
o3 Pro is proprietary; o3 Reasoning is proprietary.
Which should I choose for production?
If you need a single default, start with o3 Pro for quality-sensitive work and o3 Reasoning for high-volume, well-scoped tasks. Run both on a sample of your own traffic before locking in a choice.