Claude Opus 4.5 Turbo vs Claude Sonnet 4.5 Reasoning: which model should you choose?
We compared Claude Opus 4.5 Turbo and Claude Sonnet 4.5 Reasoning on price, context window and 12 benchmarks. Claude Sonnet 4.5 Reasoning has the stronger average benchmark score; Claude Sonnet 4.5 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
Claude Sonnet 4.5 Reasoning
Claude Sonnet 4.5 Reasoning is a frontier model from Anthropic. It offers a 400,000-token context window, costs $19.48 per million input tokens and $68.20 per million output tokens, and averages 87.7 across the index's benchmark suite.
- Input
- $19.48 / 1M
- Output
- $68.20 / 1M
- Context
- 400,000
- Avg score
- 87.7
- Open weights
- No
Specification comparison
| Spec | Claude Opus 4.5 Turbo | Claude Sonnet 4.5 Reasoning | Edge |
|---|---|---|---|
| Input price / 1M | $19.57 | $19.48 | B |
| Output price / 1M | $106.60 | $68.20 | B |
| Context window | 2,000,000 | 400,000 | A |
| Max output | 65,536 | 8,192 | A |
| Average score | 85.7 | 87.7 | B |
| Arena Elo | 1469.3 | 1486.5 | B |
| Open weights | No | No | Tie |
Benchmark comparison
Claude Opus 4.5 Turbo wins 2, Claude Sonnet 4.5 Reasoning wins 10, and 0 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | Claude Opus 4.5 Turbo | Claude Sonnet 4.5 Reasoning | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 85.8 | 87.6 | 1.8 | Claude Sonnet 4.5 Reasoning |
| GPQA Diamond | 81.9 | 85.2 | 3.3 | Claude Sonnet 4.5 Reasoning |
| SWE-bench Verified | 75.0 | 79.6 | 4.6 | Claude Sonnet 4.5 Reasoning |
| HumanEval | 89.8 | 90.3 | 0.5 | Claude Sonnet 4.5 Reasoning |
| MATH-500 | 93.2 | 89.7 | 3.5 | Claude Opus 4.5 Turbo |
| AIME 2025 | 87.2 | 87.3 | 0.1 | Claude Sonnet 4.5 Reasoning |
| LiveCodeBench | 78.5 | 85.1 | 6.6 | Claude Sonnet 4.5 Reasoning |
| IFEval | 92.2 | 91.9 | 0.3 | Claude Opus 4.5 Turbo |
| TruthfulQA | 85.5 | 87.6 | 2.1 | Claude Sonnet 4.5 Reasoning |
| HellaSwag | 92.8 | 95.2 | 2.4 | Claude Sonnet 4.5 Reasoning |
| MMMU | 80.5 | 85.2 | 4.7 | Claude Sonnet 4.5 Reasoning |
| Arena Elo | 1469.3 | 1486.5 | 17.2 | Claude Sonnet 4.5 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 Claude Sonnet 4.5 Reasoning costs about $31.66. Claude Sonnet 4.5 Reasoning is roughly 23% 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.
Claude Opus 4.5 Turbo has the larger context window at 2,000,000 tokens, compared with 400,000 for Claude Sonnet 4.5 Reasoning. That matters for long documents, large codebases and multi-step agent traces.
Verdict
Across 12 shared benchmarks, Claude Opus 4.5 Turbo wins 2, Claude Sonnet 4.5 Reasoning wins 10, and 0 are tied. On the index average, Claude Sonnet 4.5 Reasoning leads Claude Opus 4.5 Turbo by 2.0 points (87.7 versus 85.7).
The price picture favours Claude Sonnet 4.5 Reasoning. The context picture favours Claude Opus 4.5 Turbo. 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 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 need the larger 2,000,000-token context window.
- You need the larger 65,536-token output limit.
Choose Claude Sonnet 4.5 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 Claude Sonnet 4.5 Reasoning?
On the index average, Claude Sonnet 4.5 Reasoning leads Claude Opus 4.5 Turbo by 2.0 points (87.7 versus 85.7). The better choice depends on price, context and your task. Claude Opus 4.5 Turbo wins 2 benchmarks, Claude Sonnet 4.5 Reasoning wins 10.
Which is cheaper, Claude Opus 4.5 Turbo or Claude Sonnet 4.5 Reasoning?
Claude Sonnet 4.5 Reasoning is cheaper on a blended 3:1 basis at about $31.66 per million tokens, versus $41.33 for Claude Opus 4.5 Turbo.
Which has the larger context window?
Claude Opus 4.5 Turbo has the larger context window at 2,000,000 tokens. Claude Sonnet 4.5 Reasoning has 400,000 tokens.
Are these models open weights?
Claude Opus 4.5 Turbo is proprietary; Claude Sonnet 4.5 Reasoning is proprietary.
Which should I choose for production?
If you need a single default, start with Claude Sonnet 4.5 Reasoning for quality-sensitive work, and check whether its price holds at your expected volume before committing.