Claude Sonnet 4.5 Pro vs Grok 4 Pro: which model should you choose?
We compared Claude Sonnet 4.5 Pro and Grok 4 Pro on price, context window and 12 benchmarks. Claude Sonnet 4.5 Pro has the stronger average benchmark score; Grok 4 Pro is cheaper on a blended 3:1 basis.
Claude Sonnet 4.5 Pro
Claude Sonnet 4.5 Pro is a frontier model from Anthropic. It offers a 1,000,000-token context window, costs $18.73 per million input tokens and $82.29 per million output tokens, and averages 86.7 across the index's benchmark suite.
- Input
- $18.73 / 1M
- Output
- $82.29 / 1M
- Context
- 1,000,000
- Avg score
- 86.7
- 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 | Claude Sonnet 4.5 Pro | Grok 4 Pro | Edge |
|---|---|---|---|
| Input price / 1M | $18.73 | $19.00 | A |
| Output price / 1M | $82.29 | $77.72 | B |
| Context window | 1,000,000 | 1,000,000 | Tie |
| Max output | 16,384 | 128,000 | B |
| Average score | 86.7 | 85.4 | A |
| Arena Elo | 1469.0 | 1487.5 | B |
| Open weights | No | No | Tie |
Benchmark comparison
Claude Sonnet 4.5 Pro wins 7, Grok 4 Pro wins 5, and 0 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | Claude Sonnet 4.5 Pro | Grok 4 Pro | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 86.3 | 84.9 | 1.4 | Claude Sonnet 4.5 Pro |
| GPQA Diamond | 83.1 | 79.2 | 3.9 | Claude Sonnet 4.5 Pro |
| SWE-bench Verified | 73.9 | 74.7 | 0.8 | Grok 4 Pro |
| HumanEval | 92.7 | 89.7 | 3.0 | Claude Sonnet 4.5 Pro |
| MATH-500 | 90.1 | 92.3 | 2.2 | Grok 4 Pro |
| AIME 2025 | 88.4 | 85.4 | 3.0 | Claude Sonnet 4.5 Pro |
| LiveCodeBench | 81.9 | 77.8 | 4.1 | Claude Sonnet 4.5 Pro |
| IFEval | 94.1 | 91.3 | 2.8 | Claude Sonnet 4.5 Pro |
| TruthfulQA | 86.1 | 86.0 | 0.1 | Claude Sonnet 4.5 Pro |
| HellaSwag | 92.6 | 92.8 | 0.2 | Grok 4 Pro |
| MMMU | 84.5 | 84.9 | 0.4 | Grok 4 Pro |
| Arena Elo | 1469.0 | 1487.5 | 18.5 | Grok 4 Pro |
Price analysis
On a blended 3:1 input-to-output basis, Claude Sonnet 4.5 Pro costs about $34.62 per million tokens and Grok 4 Pro costs about $33.68. Grok 4 Pro is roughly 3% cheaper than Claude Sonnet 4.5 Pro. At high volume, that gap compounds quickly, so price should carry real weight unless the quality difference is decisive.
Both models list a 1,000,000-token context window. That is enough for long documents, large codebases and multi-step agent traces.
Verdict
Across 12 shared benchmarks, Claude Sonnet 4.5 Pro wins 7, Grok 4 Pro wins 5, and 0 are tied. On the index average, Claude Sonnet 4.5 Pro leads Grok 4 Pro by 1.3 points (86.7 versus 85.4).
The price picture favours Grok 4 Pro. 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 Claude Sonnet 4.5 Pro 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 Claude Sonnet 4.5 Pro if
- You want the higher average benchmark score in this index.
Choose Grok 4 Pro if
- Unit cost matters and you want the cheaper blended price.
- You need the larger 128,000-token output limit.
FAQ
Is Claude Sonnet 4.5 Pro better than Grok 4 Pro?
On the index average, Claude Sonnet 4.5 Pro leads Grok 4 Pro by 1.3 points (86.7 versus 85.4). The better choice depends on price, context and your task. Claude Sonnet 4.5 Pro wins 7 benchmarks, Grok 4 Pro wins 5.
Which is cheaper, Claude Sonnet 4.5 Pro or Grok 4 Pro?
Grok 4 Pro is cheaper on a blended 3:1 basis at about $33.68 per million tokens, versus $34.62 for Claude Sonnet 4.5 Pro.
Which has the larger context window?
Both models list a 1,000,000-token context window.
Are these models open weights?
Claude Sonnet 4.5 Pro is proprietary; Grok 4 Pro is proprietary.
Which should I choose for production?
If you need a single default, start with Claude Sonnet 4.5 Pro 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.