Claude Opus 4.5 Turbo vs Grok 4 Reasoning: which model should you choose?
We compared Claude Opus 4.5 Turbo and Grok 4 Reasoning on price, context window and 12 benchmarks. Grok 4 Reasoning has the stronger average benchmark score; Grok 4 Reasoning 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
Grok 4 Reasoning
Grok 4 Reasoning is a frontier model from xAI. It offers a 2,000,000-token context window, costs $19.67 per million input tokens and $93.29 per million output tokens, and averages 87.8 across the index's benchmark suite.
- Input
- $19.67 / 1M
- Output
- $93.29 / 1M
- Context
- 2,000,000
- Avg score
- 87.8
- Open weights
- No
Specification comparison
| Spec | Claude Opus 4.5 Turbo | Grok 4 Reasoning | Edge |
|---|---|---|---|
| Input price / 1M | $19.57 | $19.67 | A |
| Output price / 1M | $106.60 | $93.29 | B |
| Context window | 2,000,000 | 2,000,000 | Tie |
| Max output | 65,536 | 65,536 | Tie |
| Average score | 85.7 | 87.8 | B |
| Arena Elo | 1469.3 | 1487.6 | B |
| Open weights | No | No | Tie |
Benchmark comparison
Claude Opus 4.5 Turbo wins 1, Grok 4 Reasoning wins 10, and 1 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | Claude Opus 4.5 Turbo | Grok 4 Reasoning | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 85.8 | 88.5 | 2.7 | Grok 4 Reasoning |
| GPQA Diamond | 81.9 | 81.9 | 0.0 | Tie |
| SWE-bench Verified | 75.0 | 78.0 | 3.0 | Grok 4 Reasoning |
| HumanEval | 89.8 | 93.8 | 4.0 | Grok 4 Reasoning |
| MATH-500 | 93.2 | 94.4 | 1.2 | Grok 4 Reasoning |
| AIME 2025 | 87.2 | 85.6 | 1.6 | Claude Opus 4.5 Turbo |
| LiveCodeBench | 78.5 | 85.1 | 6.6 | Grok 4 Reasoning |
| IFEval | 92.2 | 93.4 | 1.2 | Grok 4 Reasoning |
| TruthfulQA | 85.5 | 89.4 | 3.9 | Grok 4 Reasoning |
| HellaSwag | 92.8 | 95.2 | 2.4 | Grok 4 Reasoning |
| MMMU | 80.5 | 80.8 | 0.3 | Grok 4 Reasoning |
| Arena Elo | 1469.3 | 1487.6 | 18.3 | Grok 4 Reasoning |
Price analysis
On a blended 3:1 input-to-output basis, Claude Opus 4.5 Turbo costs about $41.33 per million tokens and Grok 4 Reasoning costs about $38.08. Grok 4 Reasoning is roughly 8% 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 1, Grok 4 Reasoning wins 10, and 1 are tied. On the index average, Grok 4 Reasoning leads Claude Opus 4.5 Turbo by 2.1 points (87.8 versus 85.7).
The price picture favours Grok 4 Reasoning. 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 Grok 4 Reasoning 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 Grok 4 Reasoning if
- You want the higher average benchmark score in this index.
- Unit cost matters and you want the cheaper blended price.
FAQ
Is Claude Opus 4.5 Turbo better than Grok 4 Reasoning?
On the index average, Grok 4 Reasoning leads Claude Opus 4.5 Turbo by 2.1 points (87.8 versus 85.7). The better choice depends on price, context and your task. Claude Opus 4.5 Turbo wins 1 benchmarks, Grok 4 Reasoning wins 10.
Which is cheaper, Claude Opus 4.5 Turbo or Grok 4 Reasoning?
Grok 4 Reasoning is cheaper on a blended 3:1 basis at about $38.08 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; Grok 4 Reasoning is proprietary.
Which should I choose for production?
If you need a single default, start with Grok 4 Reasoning for quality-sensitive work, and check whether its price holds at your expected volume before committing.