Claude Opus 4.5 vs o4 Turbo: which model should you choose?
We compared Claude Opus 4.5 and o4 Turbo 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
o4 Turbo
o4 Turbo is a frontier model from OpenAI. It offers a 2,000,000-token context window, costs $19.34 per million input tokens and $82.19 per million output tokens, and averages 86.6 across the index's benchmark suite.
- Input
- $19.34 / 1M
- Output
- $82.19 / 1M
- Context
- 2,000,000
- Avg score
- 86.6
- Open weights
- No
Specification comparison
| Spec | Claude Opus 4.5 | o4 Turbo | Edge |
|---|---|---|---|
| Input price / 1M | $19.42 | $19.34 | B |
| Output price / 1M | $75.27 | $82.19 | A |
| Context window | 400,000 | 2,000,000 | B |
| Max output | 4,096 | 8,192 | B |
| Average score | 87.7 | 86.6 | A |
| Arena Elo | 1491.2 | 1468.1 | A |
| Open weights | No | No | Tie |
Benchmark comparison
Claude Opus 4.5 wins 7, o4 Turbo wins 5, and 0 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | Claude Opus 4.5 | o4 Turbo | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 87.0 | 88.1 | 1.1 | o4 Turbo |
| GPQA Diamond | 81.7 | 84.8 | 3.1 | o4 Turbo |
| SWE-bench Verified | 77.1 | 78.4 | 1.3 | o4 Turbo |
| HumanEval | 93.7 | 91.0 | 2.7 | Claude Opus 4.5 |
| MATH-500 | 93.7 | 91.7 | 2.0 | Claude Opus 4.5 |
| AIME 2025 | 89.8 | 85.9 | 3.9 | Claude Opus 4.5 |
| LiveCodeBench | 85.0 | 80.1 | 4.9 | Claude Opus 4.5 |
| IFEval | 92.5 | 92.6 | 0.1 | o4 Turbo |
| TruthfulQA | 88.1 | 88.8 | 0.7 | o4 Turbo |
| HellaSwag | 92.4 | 91.3 | 1.1 | Claude Opus 4.5 |
| MMMU | 84.2 | 79.6 | 4.6 | Claude Opus 4.5 |
| Arena Elo | 1491.2 | 1468.1 | 23.1 | 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 o4 Turbo costs about $35.05. Claude Opus 4.5 is roughly 5% cheaper than o4 Turbo. At high volume, that gap compounds quickly, so price should carry real weight unless the quality difference is decisive.
o4 Turbo has the larger context window at 2,000,000 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 7, o4 Turbo wins 5, and 0 are tied. On the index average, Claude Opus 4.5 leads o4 Turbo by 1.1 points (87.7 versus 86.6).
The price picture favours Claude Opus 4.5. The context picture favours o4 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 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 o4 Turbo if
- You need the larger 2,000,000-token context window.
- You need the larger 8,192-token output limit.
FAQ
Is Claude Opus 4.5 better than o4 Turbo?
On the index average, Claude Opus 4.5 leads o4 Turbo by 1.1 points (87.7 versus 86.6). The better choice depends on price, context and your task. Claude Opus 4.5 wins 7 benchmarks, o4 Turbo wins 5.
Which is cheaper, Claude Opus 4.5 or o4 Turbo?
Claude Opus 4.5 is cheaper on a blended 3:1 basis at about $33.38 per million tokens, versus $35.05 for o4 Turbo.
Which has the larger context window?
o4 Turbo has the larger context window at 2,000,000 tokens. Claude Opus 4.5 has 400,000 tokens.
Are these models open weights?
Claude Opus 4.5 is proprietary; o4 Turbo 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.