GPT-5.1 Vision vs o4: which model should you choose?
We compared GPT-5.1 Vision and o4 on price, context window and 12 benchmarks. o4 has the stronger average benchmark score; o4 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
o4
o4 is a frontier model from OpenAI. It offers a 2,000,000-token context window, costs $17.74 per million input tokens and $66.00 per million output tokens, and averages 85.4 across the index's benchmark suite.
- Input
- $17.74 / 1M
- Output
- $66.00 / 1M
- Context
- 2,000,000
- Avg score
- 85.4
- Open weights
- No
Specification comparison
| Spec | GPT-5.1 Vision | o4 | Edge |
|---|---|---|---|
| Input price / 1M | $17.76 | $17.74 | B |
| Output price / 1M | $80.59 | $66.00 | B |
| Context window | 400,000 | 2,000,000 | B |
| Max output | 16,384 | 8,192 | A |
| Average score | 84.8 | 85.4 | B |
| Arena Elo | 1462.4 | 1469.4 | B |
| Open weights | No | No | Tie |
Benchmark comparison
GPT-5.1 Vision wins 4, o4 wins 7, and 1 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | GPT-5.1 Vision | o4 | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 85.5 | 85.3 | 0.2 | GPT-5.1 Vision |
| GPQA Diamond | 78.7 | 82.3 | 3.6 | o4 |
| SWE-bench Verified | 73.6 | 74.8 | 1.2 | o4 |
| HumanEval | 89.6 | 89.6 | 0.0 | Tie |
| MATH-500 | 89.1 | 90.5 | 1.4 | o4 |
| AIME 2025 | 82.4 | 85.3 | 2.9 | o4 |
| LiveCodeBench | 77.8 | 81.4 | 3.6 | o4 |
| IFEval | 92.7 | 92.8 | 0.1 | o4 |
| TruthfulQA | 86.9 | 85.0 | 1.9 | GPT-5.1 Vision |
| HellaSwag | 92.1 | 91.0 | 1.1 | GPT-5.1 Vision |
| MMMU | 83.9 | 80.9 | 3.0 | GPT-5.1 Vision |
| Arena Elo | 1462.4 | 1469.4 | 7.0 | o4 |
Price analysis
On a blended 3:1 input-to-output basis, GPT-5.1 Vision costs about $33.47 per million tokens and o4 costs about $29.80. o4 is roughly 11% 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.
o4 has the larger context window at 2,000,000 tokens, compared with 400,000 for GPT-5.1 Vision. That matters for long documents, large codebases and multi-step agent traces.
Verdict
Across 12 shared benchmarks, GPT-5.1 Vision wins 4, o4 wins 7, and 1 are tied. On the index average, o4 leads GPT-5.1 Vision by 0.6 points (85.4 versus 84.8).
The price picture favours o4. The context picture favours o4. 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 o4 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 16,384-token output limit.
Choose o4 if
- You want the higher average benchmark score in this index.
- Unit cost matters and you want the cheaper blended price.
- You need the larger 2,000,000-token context window.
FAQ
Is GPT-5.1 Vision better than o4?
On the index average, o4 leads GPT-5.1 Vision by 0.6 points (85.4 versus 84.8). The better choice depends on price, context and your task. GPT-5.1 Vision wins 4 benchmarks, o4 wins 7.
Which is cheaper, GPT-5.1 Vision or o4?
o4 is cheaper on a blended 3:1 basis at about $29.80 per million tokens, versus $33.47 for GPT-5.1 Vision.
Which has the larger context window?
o4 has the larger context window at 2,000,000 tokens. GPT-5.1 Vision has 400,000 tokens.
Are these models open weights?
GPT-5.1 Vision is proprietary; o4 is proprietary.
Which should I choose for production?
If you need a single default, start with o4 for quality-sensitive work, and check whether its price holds at your expected volume before committing.