Claude Opus 4.5 Reasoning vs GPT-5.2 Max: which model should you choose?
We compared Claude Opus 4.5 Reasoning and GPT-5.2 Max on price, context window and 12 benchmarks. GPT-5.2 Max has the stronger average benchmark score; GPT-5.2 Max is cheaper on a blended 3:1 basis.
Claude Opus 4.5 Reasoning
Claude Opus 4.5 Reasoning is a frontier model from Anthropic. It offers a 2,000,000-token context window, costs $20.91 per million input tokens and $108.13 per million output tokens, and averages 88.2 across the index's benchmark suite.
- Input
- $20.91 / 1M
- Output
- $108.13 / 1M
- Context
- 2,000,000
- Avg score
- 88.2
- Open weights
- No
GPT-5.2 Max
GPT-5.2 Max is a frontier model from OpenAI. It offers a 1,000,000-token context window, costs $21.39 per million input tokens and $90.69 per million output tokens, and averages 89.2 across the index's benchmark suite.
- Input
- $21.39 / 1M
- Output
- $90.69 / 1M
- Context
- 1,000,000
- Avg score
- 89.2
- Open weights
- No
Specification comparison
| Spec | Claude Opus 4.5 Reasoning | GPT-5.2 Max | Edge |
|---|---|---|---|
| Input price / 1M | $20.91 | $21.39 | A |
| Output price / 1M | $108.13 | $90.69 | B |
| Context window | 2,000,000 | 1,000,000 | A |
| Max output | 16,384 | 128,000 | B |
| Average score | 88.2 | 89.2 | B |
| Arena Elo | 1497.5 | 1495.3 | A |
| Open weights | No | No | Tie |
Benchmark comparison
Claude Opus 4.5 Reasoning wins 5, GPT-5.2 Max wins 7, and 0 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | Claude Opus 4.5 Reasoning | GPT-5.2 Max | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 90.7 | 87.6 | 3.1 | Claude Opus 4.5 Reasoning |
| GPQA Diamond | 82.6 | 83.4 | 0.8 | GPT-5.2 Max |
| SWE-bench Verified | 79.5 | 80.5 | 1.0 | GPT-5.2 Max |
| HumanEval | 92.1 | 93.6 | 1.5 | GPT-5.2 Max |
| MATH-500 | 91.6 | 96.7 | 5.1 | GPT-5.2 Max |
| AIME 2025 | 88.9 | 88.2 | 0.7 | Claude Opus 4.5 Reasoning |
| LiveCodeBench | 81.8 | 84.8 | 3.0 | GPT-5.2 Max |
| IFEval | 95.9 | 95.2 | 0.7 | Claude Opus 4.5 Reasoning |
| TruthfulQA | 89.0 | 88.1 | 0.9 | Claude Opus 4.5 Reasoning |
| HellaSwag | 93.8 | 96.1 | 2.3 | GPT-5.2 Max |
| MMMU | 84.6 | 86.9 | 2.3 | GPT-5.2 Max |
| Arena Elo | 1497.5 | 1495.3 | 2.2 | Claude Opus 4.5 Reasoning |
Price analysis
On a blended 3:1 input-to-output basis, Claude Opus 4.5 Reasoning costs about $42.72 per million tokens and GPT-5.2 Max costs about $38.72. GPT-5.2 Max is roughly 9% cheaper than Claude Opus 4.5 Reasoning. At high volume, that gap compounds quickly, so price should carry real weight unless the quality difference is decisive.
Claude Opus 4.5 Reasoning has the larger context window at 2,000,000 tokens, compared with 1,000,000 for GPT-5.2 Max. That matters for long documents, large codebases and multi-step agent traces.
Verdict
Across 12 shared benchmarks, Claude Opus 4.5 Reasoning wins 5, GPT-5.2 Max wins 7, and 0 are tied. On the index average, GPT-5.2 Max leads Claude Opus 4.5 Reasoning by 1.0 points (89.2 versus 88.2).
The price picture favours GPT-5.2 Max. The context picture favours Claude Opus 4.5 Reasoning. 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 GPT-5.2 Max for quality-sensitive work, and check whether its price holds at your expected volume before committing.
Choose Claude Opus 4.5 Reasoning if
- You need the larger 2,000,000-token context window.
Choose GPT-5.2 Max 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 Reasoning better than GPT-5.2 Max?
On the index average, GPT-5.2 Max leads Claude Opus 4.5 Reasoning by 1.0 points (89.2 versus 88.2). The better choice depends on price, context and your task. Claude Opus 4.5 Reasoning wins 5 benchmarks, GPT-5.2 Max wins 7.
Which is cheaper, Claude Opus 4.5 Reasoning or GPT-5.2 Max?
GPT-5.2 Max is cheaper on a blended 3:1 basis at about $38.72 per million tokens, versus $42.72 for Claude Opus 4.5 Reasoning.
Which has the larger context window?
Claude Opus 4.5 Reasoning has the larger context window at 2,000,000 tokens. GPT-5.2 Max has 1,000,000 tokens.
Are these models open weights?
Claude Opus 4.5 Reasoning is proprietary; GPT-5.2 Max is proprietary.
Which should I choose for production?
If you need a single default, start with GPT-5.2 Max for quality-sensitive work, and check whether its price holds at your expected volume before committing.