Claude Opus 4.5 Max vs Claude Sonnet 4.5 Max: which model should you choose?
We compared Claude Opus 4.5 Max and Claude Sonnet 4.5 Max on price, context window and 12 benchmarks. Claude Opus 4.5 Max has the stronger average benchmark score; Claude Sonnet 4.5 Max is cheaper on a blended 3:1 basis.
Claude Opus 4.5 Max
Claude Opus 4.5 Max is a frontier model from Anthropic. It offers a 1,000,000-token context window, costs $20.90 per million input tokens and $106.51 per million output tokens, and averages 87.8 across the index's benchmark suite.
- Input
- $20.90 / 1M
- Output
- $106.51 / 1M
- Context
- 1,000,000
- Avg score
- 87.8
- Open weights
- No
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
Specification comparison
| Spec | Claude Opus 4.5 Max | Claude Sonnet 4.5 Max | Edge |
|---|---|---|---|
| Input price / 1M | $20.90 | $19.90 | B |
| Output price / 1M | $106.51 | $95.47 | B |
| Context window | 1,000,000 | 1,000,000 | Tie |
| Max output | 16,384 | 65,536 | B |
| Average score | 87.8 | 87.2 | A |
| Arena Elo | 1501.9 | 1474.9 | A |
| Open weights | No | No | Tie |
Benchmark comparison
Claude Opus 4.5 Max wins 7, Claude Sonnet 4.5 Max wins 5, and 0 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | Claude Opus 4.5 Max | Claude Sonnet 4.5 Max | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 89.5 | 86.1 | 3.4 | Claude Opus 4.5 Max |
| GPQA Diamond | 84.6 | 84.4 | 0.2 | Claude Opus 4.5 Max |
| SWE-bench Verified | 79.5 | 80.2 | 0.7 | Claude Sonnet 4.5 Max |
| HumanEval | 91.7 | 92.4 | 0.7 | Claude Sonnet 4.5 Max |
| MATH-500 | 94.2 | 92.8 | 1.4 | Claude Opus 4.5 Max |
| AIME 2025 | 89.3 | 85.4 | 3.9 | Claude Opus 4.5 Max |
| LiveCodeBench | 80.6 | 82.8 | 2.2 | Claude Sonnet 4.5 Max |
| IFEval | 94.5 | 92.9 | 1.6 | Claude Opus 4.5 Max |
| TruthfulQA | 86.9 | 87.3 | 0.4 | Claude Sonnet 4.5 Max |
| HellaSwag | 93.0 | 93.1 | 0.1 | Claude Sonnet 4.5 Max |
| MMMU | 82.3 | 82.0 | 0.3 | Claude Opus 4.5 Max |
| Arena Elo | 1501.9 | 1474.9 | 27.0 | Claude Opus 4.5 Max |
Price analysis
On a blended 3:1 input-to-output basis, Claude Opus 4.5 Max costs about $42.30 per million tokens and Claude Sonnet 4.5 Max costs about $38.79. Claude Sonnet 4.5 Max is roughly 8% cheaper than Claude Opus 4.5 Max. 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 Opus 4.5 Max wins 7, Claude Sonnet 4.5 Max wins 5, and 0 are tied. On the index average, Claude Opus 4.5 Max leads Claude Sonnet 4.5 Max by 0.6 points (87.8 versus 87.2).
The price picture favours Claude Sonnet 4.5 Max. 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 Opus 4.5 Max for quality-sensitive work and Claude Sonnet 4.5 Max for high-volume, well-scoped tasks. Run both on a sample of your own traffic before locking in a choice.
Choose Claude Opus 4.5 Max if
- You want the higher average benchmark score in this index.
Choose Claude Sonnet 4.5 Max if
- Unit cost matters and you want the cheaper blended price.
- You need the larger 65,536-token output limit.
FAQ
Is Claude Opus 4.5 Max better than Claude Sonnet 4.5 Max?
On the index average, Claude Opus 4.5 Max 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 Opus 4.5 Max wins 7 benchmarks, Claude Sonnet 4.5 Max wins 5.
Which is cheaper, Claude Opus 4.5 Max or Claude Sonnet 4.5 Max?
Claude Sonnet 4.5 Max is cheaper on a blended 3:1 basis at about $38.79 per million tokens, versus $42.30 for Claude Opus 4.5 Max.
Which has the larger context window?
Both models list a 1,000,000-token context window.
Are these models open weights?
Claude Opus 4.5 Max is proprietary; Claude Sonnet 4.5 Max is proprietary.
Which should I choose for production?
If you need a single default, start with Claude Opus 4.5 Max for quality-sensitive work and Claude Sonnet 4.5 Max for high-volume, well-scoped tasks. Run both on a sample of your own traffic before locking in a choice.