Claude Opus 4.5 Reasoning vs GPT-5.2 Pro: which model should you choose?
We compared Claude Opus 4.5 Reasoning and GPT-5.2 Pro on price, context window and 12 benchmarks. GPT-5.2 Pro has the stronger average benchmark score; GPT-5.2 Pro 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 Pro
GPT-5.2 Pro is a frontier model from OpenAI. It offers a 2,000,000-token context window, costs $21.32 per million input tokens and $76.33 per million output tokens, and averages 89.6 across the index's benchmark suite.
- Input
- $21.32 / 1M
- Output
- $76.33 / 1M
- Context
- 2,000,000
- Avg score
- 89.6
- Open weights
- No
Specification comparison
| Spec | Claude Opus 4.5 Reasoning | GPT-5.2 Pro | Edge |
|---|---|---|---|
| Input price / 1M | $20.91 | $21.32 | A |
| Output price / 1M | $108.13 | $76.33 | B |
| Context window | 2,000,000 | 2,000,000 | Tie |
| Max output | 16,384 | 32,768 | B |
| Average score | 88.2 | 89.6 | B |
| Arena Elo | 1497.5 | 1485.0 | A |
| Open weights | No | No | Tie |
Benchmark comparison
Claude Opus 4.5 Reasoning wins 3, GPT-5.2 Pro wins 9, 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 Pro | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 90.7 | 91.6 | 0.9 | GPT-5.2 Pro |
| GPQA Diamond | 82.6 | 83.2 | 0.6 | GPT-5.2 Pro |
| SWE-bench Verified | 79.5 | 81.7 | 2.2 | GPT-5.2 Pro |
| HumanEval | 92.1 | 96.8 | 4.7 | GPT-5.2 Pro |
| MATH-500 | 91.6 | 91.8 | 0.2 | GPT-5.2 Pro |
| AIME 2025 | 88.9 | 91.0 | 2.1 | GPT-5.2 Pro |
| LiveCodeBench | 81.8 | 84.6 | 2.8 | GPT-5.2 Pro |
| IFEval | 95.9 | 95.6 | 0.3 | Claude Opus 4.5 Reasoning |
| TruthfulQA | 89.0 | 90.0 | 1.0 | GPT-5.2 Pro |
| HellaSwag | 93.8 | 95.3 | 1.5 | GPT-5.2 Pro |
| MMMU | 84.6 | 84.4 | 0.2 | Claude Opus 4.5 Reasoning |
| Arena Elo | 1497.5 | 1485.0 | 12.5 | 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 Pro costs about $35.07. GPT-5.2 Pro is roughly 18% 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.
Both models list a 2,000,000-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 Reasoning wins 3, GPT-5.2 Pro wins 9, and 0 are tied. On the index average, GPT-5.2 Pro leads Claude Opus 4.5 Reasoning by 1.4 points (89.6 versus 88.2).
The price picture favours GPT-5.2 Pro. 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 GPT-5.2 Pro for quality-sensitive work, and check whether its price holds at your expected volume before committing.
Choose Claude Opus 4.5 Reasoning if
- You prefer Anthropic's tooling or already use it.
Choose GPT-5.2 Pro 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 32,768-token output limit.
FAQ
Is Claude Opus 4.5 Reasoning better than GPT-5.2 Pro?
On the index average, GPT-5.2 Pro leads Claude Opus 4.5 Reasoning by 1.4 points (89.6 versus 88.2). The better choice depends on price, context and your task. Claude Opus 4.5 Reasoning wins 3 benchmarks, GPT-5.2 Pro wins 9.
Which is cheaper, Claude Opus 4.5 Reasoning or GPT-5.2 Pro?
GPT-5.2 Pro is cheaper on a blended 3:1 basis at about $35.07 per million tokens, versus $42.72 for Claude Opus 4.5 Reasoning.
Which has the larger context window?
Both models list a 2,000,000-token context window.
Are these models open weights?
Claude Opus 4.5 Reasoning is proprietary; GPT-5.2 Pro is proprietary.
Which should I choose for production?
If you need a single default, start with GPT-5.2 Pro for quality-sensitive work, and check whether its price holds at your expected volume before committing.