Claude Sonnet 4.5 Max vs Grok 4 Reasoning: which model should you choose?
We compared Claude Sonnet 4.5 Max 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 Sonnet 4.5 Max
Claude Sonnet 4.5 Max is a frontier model from Anthropic. It offers a 1,000,000-token context window, costs $19.90 per million input tokens and $95.47 per million output tokens, and averages 87.2 across the index's benchmark suite.
- Input
- $19.90 / 1M
- Output
- $95.47 / 1M
- Context
- 1,000,000
- Avg score
- 87.2
- 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 Sonnet 4.5 Max | Grok 4 Reasoning | Edge |
|---|---|---|---|
| Input price / 1M | $19.90 | $19.67 | B |
| Output price / 1M | $95.47 | $93.29 | B |
| Context window | 1,000,000 | 2,000,000 | B |
| Max output | 65,536 | 65,536 | Tie |
| Average score | 87.2 | 87.8 | B |
| Arena Elo | 1474.9 | 1487.6 | B |
| Open weights | No | No | Tie |
Benchmark comparison
Claude Sonnet 4.5 Max wins 3, Grok 4 Reasoning wins 9, and 0 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | Claude Sonnet 4.5 Max | Grok 4 Reasoning | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 86.1 | 88.5 | 2.4 | Grok 4 Reasoning |
| GPQA Diamond | 84.4 | 81.9 | 2.5 | Claude Sonnet 4.5 Max |
| SWE-bench Verified | 80.2 | 78.0 | 2.2 | Claude Sonnet 4.5 Max |
| HumanEval | 92.4 | 93.8 | 1.4 | Grok 4 Reasoning |
| MATH-500 | 92.8 | 94.4 | 1.6 | Grok 4 Reasoning |
| AIME 2025 | 85.4 | 85.6 | 0.2 | Grok 4 Reasoning |
| LiveCodeBench | 82.8 | 85.1 | 2.3 | Grok 4 Reasoning |
| IFEval | 92.9 | 93.4 | 0.5 | Grok 4 Reasoning |
| TruthfulQA | 87.3 | 89.4 | 2.1 | Grok 4 Reasoning |
| HellaSwag | 93.1 | 95.2 | 2.1 | Grok 4 Reasoning |
| MMMU | 82.0 | 80.8 | 1.2 | Claude Sonnet 4.5 Max |
| Arena Elo | 1474.9 | 1487.6 | 12.7 | Grok 4 Reasoning |
Price analysis
On a blended 3:1 input-to-output basis, Claude Sonnet 4.5 Max costs about $38.79 per million tokens and Grok 4 Reasoning costs about $38.08. Grok 4 Reasoning is roughly 2% cheaper than Claude Sonnet 4.5 Max. At high volume, that gap compounds quickly, so price should carry real weight unless the quality difference is decisive.
Grok 4 Reasoning has the larger context window at 2,000,000 tokens, compared with 1,000,000 for Claude Sonnet 4.5 Max. That matters for long documents, large codebases and multi-step agent traces.
Verdict
Across 12 shared benchmarks, Claude Sonnet 4.5 Max wins 3, Grok 4 Reasoning wins 9, and 0 are tied. On the index average, Grok 4 Reasoning leads Claude Sonnet 4.5 Max by 0.6 points (87.8 versus 87.2).
The price picture favours Grok 4 Reasoning. The context picture favours Grok 4 Reasoning. 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 Sonnet 4.5 Max 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.
- You need the larger 2,000,000-token context window.
FAQ
Is Claude Sonnet 4.5 Max better than Grok 4 Reasoning?
On the index average, Grok 4 Reasoning leads Claude Sonnet 4.5 Max by 0.6 points (87.8 versus 87.2). The better choice depends on price, context and your task. Claude Sonnet 4.5 Max wins 3 benchmarks, Grok 4 Reasoning wins 9.
Which is cheaper, Claude Sonnet 4.5 Max or Grok 4 Reasoning?
Grok 4 Reasoning is cheaper on a blended 3:1 basis at about $38.08 per million tokens, versus $38.79 for Claude Sonnet 4.5 Max.
Which has the larger context window?
Grok 4 Reasoning has the larger context window at 2,000,000 tokens. Claude Sonnet 4.5 Max has 1,000,000 tokens.
Are these models open weights?
Claude Sonnet 4.5 Max 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.