Claude Opus 4.5 Turbo vs GPT-5.1 Turbo: which model should you choose?
We compared Claude Opus 4.5 Turbo and GPT-5.1 Turbo on price, context window and 12 benchmarks. GPT-5.1 Turbo has the stronger average benchmark score; GPT-5.1 Turbo is cheaper on a blended 3:1 basis.
Claude Opus 4.5 Turbo
Claude Opus 4.5 Turbo is a frontier model from Anthropic. It offers a 2,000,000-token context window, costs $19.57 per million input tokens and $106.60 per million output tokens, and averages 85.7 across the index's benchmark suite.
- Input
- $19.57 / 1M
- Output
- $106.60 / 1M
- Context
- 2,000,000
- Avg score
- 85.7
- Open weights
- No
GPT-5.1 Turbo
GPT-5.1 Turbo is a frontier model from OpenAI. It offers a 2,000,000-token context window, costs $19.19 per million input tokens and $89.83 per million output tokens, and averages 86.1 across the index's benchmark suite.
- Input
- $19.19 / 1M
- Output
- $89.83 / 1M
- Context
- 2,000,000
- Avg score
- 86.1
- Open weights
- No
Specification comparison
| Spec | Claude Opus 4.5 Turbo | GPT-5.1 Turbo | Edge |
|---|---|---|---|
| Input price / 1M | $19.57 | $19.19 | B |
| Output price / 1M | $106.60 | $89.83 | B |
| Context window | 2,000,000 | 2,000,000 | Tie |
| Max output | 65,536 | 128,000 | B |
| Average score | 85.7 | 86.1 | B |
| Arena Elo | 1469.3 | 1482.0 | B |
| Open weights | No | No | Tie |
Benchmark comparison
Claude Opus 4.5 Turbo wins 7, GPT-5.1 Turbo wins 5, and 0 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | Claude Opus 4.5 Turbo | GPT-5.1 Turbo | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 85.8 | 85.2 | 0.6 | Claude Opus 4.5 Turbo |
| GPQA Diamond | 81.9 | 81.3 | 0.6 | Claude Opus 4.5 Turbo |
| SWE-bench Verified | 75.0 | 74.7 | 0.3 | Claude Opus 4.5 Turbo |
| HumanEval | 89.8 | 91.5 | 1.7 | GPT-5.1 Turbo |
| MATH-500 | 93.2 | 91.4 | 1.8 | Claude Opus 4.5 Turbo |
| AIME 2025 | 87.2 | 84.7 | 2.5 | Claude Opus 4.5 Turbo |
| LiveCodeBench | 78.5 | 84.6 | 6.1 | GPT-5.1 Turbo |
| IFEval | 92.2 | 93.4 | 1.2 | GPT-5.1 Turbo |
| TruthfulQA | 85.5 | 89.2 | 3.7 | GPT-5.1 Turbo |
| HellaSwag | 92.8 | 91.3 | 1.5 | Claude Opus 4.5 Turbo |
| MMMU | 80.5 | 79.7 | 0.8 | Claude Opus 4.5 Turbo |
| Arena Elo | 1469.3 | 1482.0 | 12.7 | GPT-5.1 Turbo |
Price analysis
On a blended 3:1 input-to-output basis, Claude Opus 4.5 Turbo costs about $41.33 per million tokens and GPT-5.1 Turbo costs about $36.85. GPT-5.1 Turbo is roughly 11% cheaper than Claude Opus 4.5 Turbo. At high volume, that gap compounds quickly, so price should carry real weight unless the quality difference is decisive.
Both models list a 2,000,000-token context window. That is enough for long documents, large codebases and multi-step agent traces.
Verdict
Across 12 shared benchmarks, Claude Opus 4.5 Turbo wins 7, GPT-5.1 Turbo wins 5, and 0 are tied. On the index average, GPT-5.1 Turbo leads Claude Opus 4.5 Turbo by 0.4 points (86.1 versus 85.7).
The price picture favours GPT-5.1 Turbo. 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-5.1 Turbo for quality-sensitive work, and check whether its price holds at your expected volume before committing.
Choose Claude Opus 4.5 Turbo if
- You prefer Anthropic's tooling or already use it.
Choose GPT-5.1 Turbo 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 128,000-token output limit.
FAQ
Is Claude Opus 4.5 Turbo better than GPT-5.1 Turbo?
On the index average, GPT-5.1 Turbo leads Claude Opus 4.5 Turbo by 0.4 points (86.1 versus 85.7). The better choice depends on price, context and your task. Claude Opus 4.5 Turbo wins 7 benchmarks, GPT-5.1 Turbo wins 5.
Which is cheaper, Claude Opus 4.5 Turbo or GPT-5.1 Turbo?
GPT-5.1 Turbo is cheaper on a blended 3:1 basis at about $36.85 per million tokens, versus $41.33 for Claude Opus 4.5 Turbo.
Which has the larger context window?
Both models list a 2,000,000-token context window.
Are these models open weights?
Claude Opus 4.5 Turbo is proprietary; GPT-5.1 Turbo is proprietary.
Which should I choose for production?
If you need a single default, start with GPT-5.1 Turbo for quality-sensitive work, and check whether its price holds at your expected volume before committing.