Claude Sonnet 4.5 Vision vs Gemini 2.5 Pro Reasoning: which model should you choose?
We compared Claude Sonnet 4.5 Vision and Gemini 2.5 Pro Reasoning on price, context window and 12 benchmarks. Claude Sonnet 4.5 Vision and Gemini 2.5 Pro Reasoning are effectively tied on the index average; Gemini 2.5 Pro Reasoning is cheaper on a blended 3:1 basis.
Claude Sonnet 4.5 Vision
Claude Sonnet 4.5 Vision is a frontier model from Anthropic. It offers a 128,000-token context window, costs $16.99 per million input tokens and $82.33 per million output tokens, and averages 83.8 across the index's benchmark suite.
- Input
- $16.99 / 1M
- Output
- $82.33 / 1M
- Context
- 128,000
- Avg score
- 83.8
- Open weights
- No
Gemini 2.5 Pro Reasoning
Gemini 2.5 Pro Reasoning is a frontier model from Google DeepMind. It offers a 128,000-token context window, costs $16.81 per million input tokens and $67.95 per million output tokens, and averages 83.8 across the index's benchmark suite.
- Input
- $16.81 / 1M
- Output
- $67.95 / 1M
- Context
- 128,000
- Avg score
- 83.8
- Open weights
- No
Specification comparison
| Spec | Claude Sonnet 4.5 Vision | Gemini 2.5 Pro Reasoning | Edge |
|---|---|---|---|
| Input price / 1M | $16.99 | $16.81 | B |
| Output price / 1M | $82.33 | $67.95 | B |
| Context window | 128,000 | 128,000 | Tie |
| Max output | 16,384 | 4,096 | A |
| Average score | 83.8 | 83.8 | Tie |
| Arena Elo | 1447.6 | 1472.1 | B |
| Open weights | No | No | Tie |
Benchmark comparison
Claude Sonnet 4.5 Vision wins 5, Gemini 2.5 Pro Reasoning wins 7, and 0 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | Claude Sonnet 4.5 Vision | Gemini 2.5 Pro Reasoning | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 84.8 | 86.8 | 2.0 | Gemini 2.5 Pro Reasoning |
| GPQA Diamond | 79.6 | 80.0 | 0.4 | Gemini 2.5 Pro Reasoning |
| SWE-bench Verified | 73.7 | 71.2 | 2.5 | Claude Sonnet 4.5 Vision |
| HumanEval | 87.0 | 86.7 | 0.3 | Claude Sonnet 4.5 Vision |
| MATH-500 | 90.6 | 87.9 | 2.7 | Claude Sonnet 4.5 Vision |
| AIME 2025 | 86.4 | 84.2 | 2.2 | Claude Sonnet 4.5 Vision |
| LiveCodeBench | 76.5 | 74.8 | 1.7 | Claude Sonnet 4.5 Vision |
| IFEval | 89.9 | 90.8 | 0.9 | Gemini 2.5 Pro Reasoning |
| TruthfulQA | 83.7 | 84.0 | 0.3 | Gemini 2.5 Pro Reasoning |
| HellaSwag | 89.4 | 92.1 | 2.7 | Gemini 2.5 Pro Reasoning |
| MMMU | 79.7 | 82.8 | 3.1 | Gemini 2.5 Pro Reasoning |
| Arena Elo | 1447.6 | 1472.1 | 24.5 | Gemini 2.5 Pro Reasoning |
Price analysis
On a blended 3:1 input-to-output basis, Claude Sonnet 4.5 Vision costs about $33.33 per million tokens and Gemini 2.5 Pro Reasoning costs about $29.59. Gemini 2.5 Pro Reasoning is roughly 11% cheaper than Claude Sonnet 4.5 Vision. At high volume, that gap compounds quickly, so price should carry real weight unless the quality difference is decisive.
Both models list a 128,000-token context window. That is enough for long documents, large codebases and multi-step agent traces.
Verdict
Across 12 shared benchmarks, Claude Sonnet 4.5 Vision wins 5, Gemini 2.5 Pro Reasoning wins 7, and 0 are tied. The two models are effectively tied on the index average at 83.8.
The price picture favours Gemini 2.5 Pro Reasoning. 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 Gemini 2.5 Pro Reasoning if cost is the constraint and Claude Sonnet 4.5 Vision if context is the constraint. Test both on a sample of your own traffic before committing.
Choose Claude Sonnet 4.5 Vision if
- You need the larger 16,384-token output limit.
Choose Gemini 2.5 Pro Reasoning if
- Unit cost matters and you want the cheaper blended price.
FAQ
Is Claude Sonnet 4.5 Vision better than Gemini 2.5 Pro Reasoning?
The two models are effectively tied on the index average at 83.8. The better choice depends on price, context and your task. Claude Sonnet 4.5 Vision wins 5 benchmarks, Gemini 2.5 Pro Reasoning wins 7.
Which is cheaper, Claude Sonnet 4.5 Vision or Gemini 2.5 Pro Reasoning?
Gemini 2.5 Pro Reasoning is cheaper on a blended 3:1 basis at about $29.59 per million tokens, versus $33.33 for Claude Sonnet 4.5 Vision.
Which has the larger context window?
Both models list a 128,000-token context window.
Are these models open weights?
Claude Sonnet 4.5 Vision is proprietary; Gemini 2.5 Pro Reasoning is proprietary.
Which should I choose for production?
If you need a single default, start with Gemini 2.5 Pro Reasoning if cost is the constraint and Claude Sonnet 4.5 Vision if context is the constraint. Test both on a sample of your own traffic before committing.