GPT-5.1 Vision vs o3 Reasoning: which model should you choose?
We compared GPT-5.1 Vision and o3 Reasoning on price, context window and 12 benchmarks. o3 Reasoning has the stronger average benchmark score; o3 Reasoning is cheaper on a blended 3:1 basis.
GPT-5.1 Vision
GPT-5.1 Vision is a frontier model from OpenAI. It offers a 400,000-token context window, costs $17.76 per million input tokens and $80.59 per million output tokens, and averages 84.8 across the index's benchmark suite.
- Input
- $17.76 / 1M
- Output
- $80.59 / 1M
- Context
- 400,000
- Avg score
- 84.8
- 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 | GPT-5.1 Vision | o3 Reasoning | Edge |
|---|---|---|---|
| Input price / 1M | $17.76 | $18.07 | A |
| Output price / 1M | $80.59 | $70.65 | B |
| Context window | 400,000 | 200,000 | A |
| Max output | 16,384 | 16,384 | Tie |
| Average score | 84.8 | 85.3 | B |
| Arena Elo | 1462.4 | 1456.9 | A |
| Open weights | No | No | Tie |
Benchmark comparison
GPT-5.1 Vision wins 6, o3 Reasoning wins 6, and 0 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | GPT-5.1 Vision | o3 Reasoning | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 85.5 | 87.7 | 2.2 | o3 Reasoning |
| GPQA Diamond | 78.7 | 79.6 | 0.9 | o3 Reasoning |
| SWE-bench Verified | 73.6 | 74.1 | 0.5 | o3 Reasoning |
| HumanEval | 89.6 | 91.3 | 1.7 | o3 Reasoning |
| MATH-500 | 89.1 | 92.0 | 2.9 | o3 Reasoning |
| AIME 2025 | 82.4 | 80.5 | 1.9 | GPT-5.1 Vision |
| LiveCodeBench | 77.8 | 82.7 | 4.9 | o3 Reasoning |
| IFEval | 92.7 | 90.6 | 2.1 | GPT-5.1 Vision |
| TruthfulQA | 86.9 | 86.5 | 0.4 | GPT-5.1 Vision |
| HellaSwag | 92.1 | 90.9 | 1.2 | GPT-5.1 Vision |
| MMMU | 83.9 | 82.3 | 1.6 | GPT-5.1 Vision |
| Arena Elo | 1462.4 | 1456.9 | 5.5 | GPT-5.1 Vision |
Price analysis
On a blended 3:1 input-to-output basis, GPT-5.1 Vision costs about $33.47 per million tokens and o3 Reasoning costs about $31.22. o3 Reasoning is roughly 7% cheaper than GPT-5.1 Vision. At high volume, that gap compounds quickly, so price should carry real weight unless the quality difference is decisive.
GPT-5.1 Vision 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, GPT-5.1 Vision wins 6, o3 Reasoning wins 6, and 0 are tied. On the index average, o3 Reasoning leads GPT-5.1 Vision by 0.5 points (85.3 versus 84.8).
The price picture favours o3 Reasoning. The context picture favours GPT-5.1 Vision. 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 Reasoning for quality-sensitive work, and check whether its price holds at your expected volume before committing.
Choose GPT-5.1 Vision if
- You need the larger 400,000-token context window.
Choose o3 Reasoning if
- You want the higher average benchmark score in this index.
- Unit cost matters and you want the cheaper blended price.
FAQ
Is GPT-5.1 Vision better than o3 Reasoning?
On the index average, o3 Reasoning leads GPT-5.1 Vision by 0.5 points (85.3 versus 84.8). The better choice depends on price, context and your task. GPT-5.1 Vision wins 6 benchmarks, o3 Reasoning wins 6.
Which is cheaper, GPT-5.1 Vision or o3 Reasoning?
o3 Reasoning is cheaper on a blended 3:1 basis at about $31.22 per million tokens, versus $33.47 for GPT-5.1 Vision.
Which has the larger context window?
GPT-5.1 Vision has the larger context window at 400,000 tokens. o3 Reasoning has 200,000 tokens.
Are these models open weights?
GPT-5.1 Vision is proprietary; o3 Reasoning is proprietary.
Which should I choose for production?
If you need a single default, start with o3 Reasoning for quality-sensitive work, and check whether its price holds at your expected volume before committing.