GPT-5.1 Turbo vs Grok 4 Pro: which model should you choose?
We compared GPT-5.1 Turbo and Grok 4 Pro on price, context window and 12 benchmarks. GPT-5.1 Turbo has the stronger average benchmark score; Grok 4 Pro is cheaper on a blended 3:1 basis.
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
Grok 4 Pro
Grok 4 Pro is a frontier model from xAI. It offers a 1,000,000-token context window, costs $19.00 per million input tokens and $77.72 per million output tokens, and averages 85.4 across the index's benchmark suite.
- Input
- $19.00 / 1M
- Output
- $77.72 / 1M
- Context
- 1,000,000
- Avg score
- 85.4
- Open weights
- No
Specification comparison
| Spec | GPT-5.1 Turbo | Grok 4 Pro | Edge |
|---|---|---|---|
| Input price / 1M | $19.19 | $19.00 | B |
| Output price / 1M | $89.83 | $77.72 | B |
| Context window | 2,000,000 | 1,000,000 | A |
| Max output | 128,000 | 128,000 | Tie |
| Average score | 86.1 | 85.4 | A |
| Arena Elo | 1482.0 | 1487.5 | B |
| Open weights | No | No | Tie |
Benchmark comparison
GPT-5.1 Turbo wins 6, Grok 4 Pro wins 5, and 1 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | GPT-5.1 Turbo | Grok 4 Pro | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 85.2 | 84.9 | 0.3 | GPT-5.1 Turbo |
| GPQA Diamond | 81.3 | 79.2 | 2.1 | GPT-5.1 Turbo |
| SWE-bench Verified | 74.7 | 74.7 | 0.0 | Tie |
| HumanEval | 91.5 | 89.7 | 1.8 | GPT-5.1 Turbo |
| MATH-500 | 91.4 | 92.3 | 0.9 | Grok 4 Pro |
| AIME 2025 | 84.7 | 85.4 | 0.7 | Grok 4 Pro |
| LiveCodeBench | 84.6 | 77.8 | 6.8 | GPT-5.1 Turbo |
| IFEval | 93.4 | 91.3 | 2.1 | GPT-5.1 Turbo |
| TruthfulQA | 89.2 | 86.0 | 3.2 | GPT-5.1 Turbo |
| HellaSwag | 91.3 | 92.8 | 1.5 | Grok 4 Pro |
| MMMU | 79.7 | 84.9 | 5.2 | Grok 4 Pro |
| Arena Elo | 1482.0 | 1487.5 | 5.5 | Grok 4 Pro |
Price analysis
On a blended 3:1 input-to-output basis, GPT-5.1 Turbo costs about $36.85 per million tokens and Grok 4 Pro costs about $33.68. Grok 4 Pro is roughly 9% cheaper than GPT-5.1 Turbo. At high volume, that gap compounds quickly, so price should carry real weight unless the quality difference is decisive.
GPT-5.1 Turbo has the larger context window at 2,000,000 tokens, compared with 1,000,000 for Grok 4 Pro. That matters for long documents, large codebases and multi-step agent traces.
Verdict
Across 12 shared benchmarks, GPT-5.1 Turbo wins 6, Grok 4 Pro wins 5, and 1 are tied. On the index average, GPT-5.1 Turbo leads Grok 4 Pro by 0.7 points (86.1 versus 85.4).
The price picture favours Grok 4 Pro. The context picture favours GPT-5.1 Turbo. 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 Grok 4 Pro for high-volume, well-scoped tasks. Run both on a sample of your own traffic before locking in a choice.
Choose GPT-5.1 Turbo if
- You want the higher average benchmark score in this index.
- You need the larger 2,000,000-token context window.
Choose Grok 4 Pro if
- Unit cost matters and you want the cheaper blended price.
FAQ
Is GPT-5.1 Turbo better than Grok 4 Pro?
On the index average, GPT-5.1 Turbo leads Grok 4 Pro by 0.7 points (86.1 versus 85.4). The better choice depends on price, context and your task. GPT-5.1 Turbo wins 6 benchmarks, Grok 4 Pro wins 5.
Which is cheaper, GPT-5.1 Turbo or Grok 4 Pro?
Grok 4 Pro is cheaper on a blended 3:1 basis at about $33.68 per million tokens, versus $36.85 for GPT-5.1 Turbo.
Which has the larger context window?
GPT-5.1 Turbo has the larger context window at 2,000,000 tokens. Grok 4 Pro has 1,000,000 tokens.
Are these models open weights?
GPT-5.1 Turbo is proprietary; Grok 4 Pro 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 Grok 4 Pro for high-volume, well-scoped tasks. Run both on a sample of your own traffic before locking in a choice.