GPT-5.1 Pro: pricing, context window and benchmarks
GPT-5.1 Pro is a frontier model from OpenAI. It offers a 200,000-token context window, costs $19.77 per million input tokens and $100.32 per million output tokens, and averages 87.8 across the index's benchmark suite.
Pricing
GPT-5.1 Pro costs $19.77 per million input tokens and $100.32 per million output tokens. A blended 3:1 input-to-output mix works out to about $39.91 per million tokens. Cached input is listed at $1.75 per million tokens.
| Item | Price | Notes |
|---|---|---|
| Input | $19.77 | per 1M tokens |
| Output | $100.32 | per 1M tokens |
| Cached input | $1.75 | per 1M tokens |
| Blended 3:1 | $39.91 | estimate per 1M tokens |
| 1M in + 1M out | $120.09 | estimate |
Benchmarks
Scores below are modelled estimates on a 0–100 scale. Use them to compare relative position, not as official vendor results.
| Benchmark | Score | Rank | Percentile | Relative |
|---|---|---|---|---|
| MMLU-Pro | 86.2 | 49 | 92th | |
| GPQA Diamond | 83.4 | 16 | 97th | |
| SWE-bench Verified | 80.1 | 6 | 99th | |
| HumanEval | 91.1 | 32 | 95th | |
| MATH-500 | 95.1 | 3 | 100th | |
| AIME 2025 | 90.6 | 3 | 100th | |
| LiveCodeBench | 82.2 | 22 | 96th | |
| IFEval | 94.8 | 6 | 99th | |
| TruthfulQA | 86.9 | 39 | 94th | |
| HellaSwag | 93.8 | 15 | 98th | |
| MMMU | 81.6 | 36 | 94th | |
| Arena Elo | 1490.0 | 9 | 99th |
What GPT-5.1 Pro is good for
GPT-5.1 Pro sits in the frontier tier of the index. It is aimed at work where answer quality matters more than unit cost: hard reasoning, multi-step coding, document analysis and multimodal inputs. At $19.77 per million input tokens and a 200,000-token context window, it is a premium option, so reserve it for tasks where a cheaper model measurably fails.
Strengths
- Top-tier average benchmark score (87.8), placing it #10 of 600.
- Large 200,000-token context window for long documents and agent traces.
- Accepts more than text, including image input where the provider supports it.
- Reasoning-oriented profile, useful for multi-step problems and structured analysis.
- Coding benchmarks are a relative strength within its tier.
Trade-offs
- Proprietary licence: you cannot download the weights or self-host the model.
- Premium input pricing at $19.77 per million tokens.
- Cost can climb quickly on long outputs and high-volume traffic.
How it compares
| Model | Provider | Context | Input / 1M | Avg score |
|---|---|---|---|---|
| GPT-5.1 Max | OpenAI | 2000000 | $20.50 | 87.9 |
| Claude Opus 4.5 Max | Anthropic | 1000000 | $20.90 | 87.8 |
| GPT-5.1 Pro | OpenAI | 200000 | $19.77 | 87.8 |
| Grok 4 Reasoning | xAI | 2000000 | $19.67 | 87.8 |
| Claude Opus 4.5 | Anthropic | 400000 | $19.42 | 87.7 |
| Claude Sonnet 4.5 Reasoning | Anthropic | 400000 | $19.48 | 87.7 |
FAQ
How much does GPT-5.1 Pro cost?
GPT-5.1 Pro is listed at $19.77 per million input tokens and $100.32 per million output tokens. Cached input is $1.75 per million tokens. A blended 3:1 input-to-output mix is about $39.91 per million tokens.
What is the context window of GPT-5.1 Pro?
GPT-5.1 Pro has a context window of 200,000 tokens and can emit up to 32,768 output tokens per request in this index.
Is GPT-5.1 Pro open weights?
No. GPT-5.1 Pro is a proprietary model with a proprietary licence, so you cannot download the weights.
How does GPT-5.1 Pro score on benchmarks?
GPT-5.1 Pro averages 87.8 across the scored benchmarks in this index, ranking #10 of 600 models. Its strongest relative result is Arena Elo at 1490.0.
What is GPT-5.1 Pro best for?
GPT-5.1 Pro sits in the frontier tier of the index. It is aimed at work where answer quality matters more than unit cost: hard reasoning, multi-step coding, document analysis and multimodal inputs. At $19.77 per million input tokens and a 200,000-token context window, it is a premium option, so reserve it for tasks where a cheaper model measurably fails.