GPT-4.1 Pro vs GPT-5.1 Vision: which model should you choose?
We compared GPT-4.1 Pro and GPT-5.1 Vision on price, context window and 12 benchmarks. GPT-4.1 Pro has the stronger average benchmark score; GPT-5.1 Vision is cheaper on a blended 3:1 basis.
GPT-4.1 Pro
GPT-4.1 Pro is a frontier model from OpenAI. It offers a 400,000-token context window, costs $17.56 per million input tokens and $91.14 per million output tokens, and averages 85.2 across the index's benchmark suite.
- Input
- $17.56 / 1M
- Output
- $91.14 / 1M
- Context
- 400,000
- Avg score
- 85.2
- Open weights
- No
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
Specification comparison
| Spec | GPT-4.1 Pro | GPT-5.1 Vision | Edge |
|---|---|---|---|
| Input price / 1M | $17.56 | $17.76 | A |
| Output price / 1M | $91.14 | $80.59 | B |
| Context window | 400,000 | 400,000 | Tie |
| Max output | 8,192 | 16,384 | B |
| Average score | 85.2 | 84.8 | A |
| Arena Elo | 1449.6 | 1462.4 | B |
| Open weights | No | No | Tie |
Benchmark comparison
GPT-4.1 Pro wins 6, GPT-5.1 Vision wins 6, and 0 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | GPT-4.1 Pro | GPT-5.1 Vision | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 86.9 | 85.5 | 1.4 | GPT-4.1 Pro |
| GPQA Diamond | 78.2 | 78.7 | 0.5 | GPT-5.1 Vision |
| SWE-bench Verified | 77.3 | 73.6 | 3.7 | GPT-4.1 Pro |
| HumanEval | 91.9 | 89.6 | 2.3 | GPT-4.1 Pro |
| MATH-500 | 88.8 | 89.1 | 0.3 | GPT-5.1 Vision |
| AIME 2025 | 82.8 | 82.4 | 0.4 | GPT-4.1 Pro |
| LiveCodeBench | 76.7 | 77.8 | 1.1 | GPT-5.1 Vision |
| IFEval | 92.2 | 92.7 | 0.5 | GPT-5.1 Vision |
| TruthfulQA | 87.7 | 86.9 | 0.8 | GPT-4.1 Pro |
| HellaSwag | 93.7 | 92.1 | 1.6 | GPT-4.1 Pro |
| MMMU | 81.5 | 83.9 | 2.4 | GPT-5.1 Vision |
| Arena Elo | 1449.6 | 1462.4 | 12.8 | GPT-5.1 Vision |
Price analysis
On a blended 3:1 input-to-output basis, GPT-4.1 Pro costs about $35.95 per million tokens and GPT-5.1 Vision costs about $33.47. GPT-5.1 Vision is roughly 7% cheaper than GPT-4.1 Pro. At high volume, that gap compounds quickly, so price should carry real weight unless the quality difference is decisive.
Both models list a 400,000-token context window. That is enough for long documents, large codebases and multi-step agent traces.
Verdict
Across 12 shared benchmarks, GPT-4.1 Pro wins 6, GPT-5.1 Vision wins 6, and 0 are tied. On the index average, GPT-4.1 Pro leads GPT-5.1 Vision by 0.4 points (85.2 versus 84.8).
The price picture favours GPT-5.1 Vision. The context picture is effectively a tie. 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 GPT-4.1 Pro for quality-sensitive work and GPT-5.1 Vision for high-volume, well-scoped tasks. Run both on a sample of your own traffic before locking in a choice.
Choose GPT-4.1 Pro if
- You want the higher average benchmark score in this index.
Choose GPT-5.1 Vision if
- Unit cost matters and you want the cheaper blended price.
- You need the larger 16,384-token output limit.
FAQ
Is GPT-4.1 Pro better than GPT-5.1 Vision?
On the index average, GPT-4.1 Pro leads GPT-5.1 Vision by 0.4 points (85.2 versus 84.8). The better choice depends on price, context and your task. GPT-4.1 Pro wins 6 benchmarks, GPT-5.1 Vision wins 6.
Which is cheaper, GPT-4.1 Pro or GPT-5.1 Vision?
GPT-5.1 Vision is cheaper on a blended 3:1 basis at about $33.47 per million tokens, versus $35.95 for GPT-4.1 Pro.
Which has the larger context window?
Both models list a 400,000-token context window.
Are these models open weights?
GPT-4.1 Pro is proprietary; GPT-5.1 Vision is proprietary.
Which should I choose for production?
If you need a single default, start with GPT-4.1 Pro for quality-sensitive work and GPT-5.1 Vision for high-volume, well-scoped tasks. Run both on a sample of your own traffic before locking in a choice.