Claude Opus 4.5 Turbo vs o4 Reasoning: which model should you choose?
We compared Claude Opus 4.5 Turbo and o4 Reasoning on price, context window and 12 benchmarks. o4 Reasoning has the stronger average benchmark score; o4 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
o4 Reasoning
o4 Reasoning is a frontier model from OpenAI. It offers a 1,000,000-token context window, costs $19.69 per million input tokens and $103.53 per million output tokens, and averages 87.5 across the index's benchmark suite.
- Input
- $19.69 / 1M
- Output
- $103.53 / 1M
- Context
- 1,000,000
- Avg score
- 87.5
- Open weights
- No
Specification comparison
| Spec | Claude Opus 4.5 Turbo | o4 Reasoning | Edge |
|---|---|---|---|
| Input price / 1M | $19.57 | $19.69 | A |
| Output price / 1M | $106.60 | $103.53 | B |
| Context window | 2,000,000 | 1,000,000 | A |
| Max output | 65,536 | 128,000 | B |
| Average score | 85.7 | 87.5 | B |
| Arena Elo | 1469.3 | 1472.2 | B |
| Open weights | No | No | Tie |
Benchmark comparison
Claude Opus 4.5 Turbo wins 1, o4 Reasoning wins 11, and 0 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | Claude Opus 4.5 Turbo | o4 Reasoning | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 85.8 | 86.1 | 0.3 | o4 Reasoning |
| GPQA Diamond | 81.9 | 84.0 | 2.1 | o4 Reasoning |
| SWE-bench Verified | 75.0 | 76.4 | 1.4 | o4 Reasoning |
| HumanEval | 89.8 | 90.2 | 0.4 | o4 Reasoning |
| MATH-500 | 93.2 | 94.8 | 1.6 | o4 Reasoning |
| AIME 2025 | 87.2 | 90.3 | 3.1 | o4 Reasoning |
| LiveCodeBench | 78.5 | 83.4 | 4.9 | o4 Reasoning |
| IFEval | 92.2 | 94.5 | 2.3 | o4 Reasoning |
| TruthfulQA | 85.5 | 89.0 | 3.5 | o4 Reasoning |
| HellaSwag | 92.8 | 92.4 | 0.4 | Claude Opus 4.5 Turbo |
| MMMU | 80.5 | 81.8 | 1.3 | o4 Reasoning |
| Arena Elo | 1469.3 | 1472.2 | 2.9 | o4 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 o4 Reasoning costs about $40.65. o4 Reasoning is roughly 2% 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 1,000,000 for o4 Reasoning. That matters for long documents, large codebases and multi-step agent traces.
Verdict
Across 12 shared benchmarks, Claude Opus 4.5 Turbo wins 1, o4 Reasoning wins 11, and 0 are tied. On the index average, o4 Reasoning leads Claude Opus 4.5 Turbo by 1.8 points (87.5 versus 85.7).
The price picture favours o4 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 o4 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.
Choose o4 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 128,000-token output limit.
FAQ
Is Claude Opus 4.5 Turbo better than o4 Reasoning?
On the index average, o4 Reasoning leads Claude Opus 4.5 Turbo by 1.8 points (87.5 versus 85.7). The better choice depends on price, context and your task. Claude Opus 4.5 Turbo wins 1 benchmarks, o4 Reasoning wins 11.
Which is cheaper, Claude Opus 4.5 Turbo or o4 Reasoning?
o4 Reasoning is cheaper on a blended 3:1 basis at about $40.65 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. o4 Reasoning has 1,000,000 tokens.
Are these models open weights?
Claude Opus 4.5 Turbo is proprietary; o4 Reasoning is proprietary.
Which should I choose for production?
If you need a single default, start with o4 Reasoning for quality-sensitive work, and check whether its price holds at your expected volume before committing.