Claude Opus 4.5 vs Grok 4 Pro: which model should you choose?
We compared Claude Opus 4.5 and Grok 4 Pro on price, context window and 12 benchmarks. Claude Opus 4.5 has the stronger average benchmark score; Claude Opus 4.5 is cheaper on a blended 3:1 basis.
Claude Opus 4.5
Claude Opus 4.5 is a frontier model from Anthropic. It offers a 400,000-token context window, costs $19.42 per million input tokens and $75.27 per million output tokens, and averages 87.7 across the index's benchmark suite.
- Input
- $19.42 / 1M
- Output
- $75.27 / 1M
- Context
- 400,000
- Avg score
- 87.7
- 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 Opus 4.5 | Grok 4 Pro | Edge |
|---|---|---|---|
| Input price / 1M | $19.42 | $19.00 | B |
| Output price / 1M | $75.27 | $77.72 | A |
| Context window | 400,000 | 1,000,000 | B |
| Max output | 4,096 | 128,000 | B |
| Average score | 87.7 | 85.4 | A |
| Arena Elo | 1491.2 | 1487.5 | A |
| Open weights | No | No | Tie |
Benchmark comparison
Claude Opus 4.5 wins 10, Grok 4 Pro wins 2, and 0 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | Claude Opus 4.5 | Grok 4 Pro | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 87.0 | 84.9 | 2.1 | Claude Opus 4.5 |
| GPQA Diamond | 81.7 | 79.2 | 2.5 | Claude Opus 4.5 |
| SWE-bench Verified | 77.1 | 74.7 | 2.4 | Claude Opus 4.5 |
| HumanEval | 93.7 | 89.7 | 4.0 | Claude Opus 4.5 |
| MATH-500 | 93.7 | 92.3 | 1.4 | Claude Opus 4.5 |
| AIME 2025 | 89.8 | 85.4 | 4.4 | Claude Opus 4.5 |
| LiveCodeBench | 85.0 | 77.8 | 7.2 | Claude Opus 4.5 |
| IFEval | 92.5 | 91.3 | 1.2 | Claude Opus 4.5 |
| TruthfulQA | 88.1 | 86.0 | 2.1 | Claude Opus 4.5 |
| HellaSwag | 92.4 | 92.8 | 0.4 | Grok 4 Pro |
| MMMU | 84.2 | 84.9 | 0.7 | Grok 4 Pro |
| Arena Elo | 1491.2 | 1487.5 | 3.7 | Claude Opus 4.5 |
Price analysis
On a blended 3:1 input-to-output basis, Claude Opus 4.5 costs about $33.38 per million tokens and Grok 4 Pro costs about $33.68. Claude Opus 4.5 is roughly 1% cheaper than Grok 4 Pro. At high volume, that gap compounds quickly, so price should carry real weight unless the quality difference is decisive.
Grok 4 Pro has the larger context window at 1,000,000 tokens, compared with 400,000 for Claude Opus 4.5. That matters for long documents, large codebases and multi-step agent traces.
Verdict
Across 12 shared benchmarks, Claude Opus 4.5 wins 10, Grok 4 Pro wins 2, and 0 are tied. On the index average, Claude Opus 4.5 leads Grok 4 Pro by 2.3 points (87.7 versus 85.4).
The price picture favours Claude Opus 4.5. The context picture favours Grok 4 Pro. 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 Opus 4.5 for quality-sensitive work, and check whether its price holds at your expected volume before committing.
Choose Claude Opus 4.5 if
- You want the higher average benchmark score in this index.
- Unit cost matters and you want the cheaper blended price.
Choose Grok 4 Pro if
- You need the larger 1,000,000-token context window.
- You need the larger 128,000-token output limit.
FAQ
Is Claude Opus 4.5 better than Grok 4 Pro?
On the index average, Claude Opus 4.5 leads Grok 4 Pro by 2.3 points (87.7 versus 85.4). The better choice depends on price, context and your task. Claude Opus 4.5 wins 10 benchmarks, Grok 4 Pro wins 2.
Which is cheaper, Claude Opus 4.5 or Grok 4 Pro?
Claude Opus 4.5 is cheaper on a blended 3:1 basis at about $33.38 per million tokens, versus $33.68 for Grok 4 Pro.
Which has the larger context window?
Grok 4 Pro has the larger context window at 1,000,000 tokens. Claude Opus 4.5 has 400,000 tokens.
Are these models open weights?
Claude Opus 4.5 is proprietary; Grok 4 Pro is proprietary.
Which should I choose for production?
If you need a single default, start with Claude Opus 4.5 for quality-sensitive work, and check whether its price holds at your expected volume before committing.