Claude Sonnet 4.5 Reasoning vs GPT-5.2 Vision: which model should you choose?
We compared Claude Sonnet 4.5 Reasoning and GPT-5.2 Vision 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 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
GPT-5.2 Vision
GPT-5.2 Vision is a frontier model from OpenAI. It offers a 1,000,000-token context window, costs $19.03 per million input tokens and $85.72 per million output tokens, and averages 87.4 across the index's benchmark suite.
- Input
- $19.03 / 1M
- Output
- $85.72 / 1M
- Context
- 1,000,000
- Avg score
- 87.4
- Open weights
- No
Specification comparison
| Spec | Claude Sonnet 4.5 Reasoning | GPT-5.2 Vision | Edge |
|---|---|---|---|
| Input price / 1M | $19.48 | $19.03 | B |
| Output price / 1M | $68.20 | $85.72 | A |
| Context window | 400,000 | 1,000,000 | B |
| Max output | 8,192 | 16,384 | B |
| Average score | 87.7 | 87.4 | A |
| Arena Elo | 1486.5 | 1484.3 | A |
| Open weights | No | No | Tie |
Benchmark comparison
Claude Sonnet 4.5 Reasoning wins 8, GPT-5.2 Vision wins 4, and 0 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | Claude Sonnet 4.5 Reasoning | GPT-5.2 Vision | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 87.6 | 89.5 | 1.9 | GPT-5.2 Vision |
| GPQA Diamond | 85.2 | 82.1 | 3.1 | Claude Sonnet 4.5 Reasoning |
| SWE-bench Verified | 79.6 | 78.8 | 0.8 | Claude Sonnet 4.5 Reasoning |
| HumanEval | 90.3 | 91.2 | 0.9 | GPT-5.2 Vision |
| MATH-500 | 89.7 | 92.9 | 3.2 | GPT-5.2 Vision |
| AIME 2025 | 87.3 | 85.7 | 1.6 | Claude Sonnet 4.5 Reasoning |
| LiveCodeBench | 85.1 | 83.4 | 1.7 | Claude Sonnet 4.5 Reasoning |
| IFEval | 91.9 | 93.9 | 2.0 | GPT-5.2 Vision |
| TruthfulQA | 87.6 | 85.3 | 2.3 | Claude Sonnet 4.5 Reasoning |
| HellaSwag | 95.2 | 94.6 | 0.6 | Claude Sonnet 4.5 Reasoning |
| MMMU | 85.2 | 84.4 | 0.8 | Claude Sonnet 4.5 Reasoning |
| Arena Elo | 1486.5 | 1484.3 | 2.2 | Claude Sonnet 4.5 Reasoning |
Price analysis
On a blended 3:1 input-to-output basis, Claude Sonnet 4.5 Reasoning costs about $31.66 per million tokens and GPT-5.2 Vision costs about $35.70. Claude Sonnet 4.5 Reasoning is roughly 11% cheaper than GPT-5.2 Vision. At high volume, that gap compounds quickly, so price should carry real weight unless the quality difference is decisive.
GPT-5.2 Vision has the larger context window at 1,000,000 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 Sonnet 4.5 Reasoning wins 8, GPT-5.2 Vision wins 4, and 0 are tied. On the index average, Claude Sonnet 4.5 Reasoning leads GPT-5.2 Vision by 0.3 points (87.7 versus 87.4).
The price picture favours Claude Sonnet 4.5 Reasoning. The context picture favours GPT-5.2 Vision. 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 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.
Choose GPT-5.2 Vision if
- You need the larger 1,000,000-token context window.
- You need the larger 16,384-token output limit.
FAQ
Is Claude Sonnet 4.5 Reasoning better than GPT-5.2 Vision?
On the index average, Claude Sonnet 4.5 Reasoning leads GPT-5.2 Vision by 0.3 points (87.7 versus 87.4). The better choice depends on price, context and your task. Claude Sonnet 4.5 Reasoning wins 8 benchmarks, GPT-5.2 Vision wins 4.
Which is cheaper, Claude Sonnet 4.5 Reasoning or GPT-5.2 Vision?
Claude Sonnet 4.5 Reasoning is cheaper on a blended 3:1 basis at about $31.66 per million tokens, versus $35.70 for GPT-5.2 Vision.
Which has the larger context window?
GPT-5.2 Vision has the larger context window at 1,000,000 tokens. Claude Sonnet 4.5 Reasoning has 400,000 tokens.
Are these models open weights?
Claude Sonnet 4.5 Reasoning is proprietary; GPT-5.2 Vision 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.