Claude Sonnet 4.5 vs Gemini 3 Pro: which model should you choose?
We compared Claude Sonnet 4.5 and Gemini 3 Pro on price, context window and 12 benchmarks. Gemini 3 Pro has the stronger average benchmark score; Claude Sonnet 4.5 is cheaper on a blended 3:1 basis.
Claude Sonnet 4.5
Claude Sonnet 4.5 is a frontier model from Anthropic. It offers a 400,000-token context window, costs $17.84 per million input tokens and $70.50 per million output tokens, and averages 86.0 across the index's benchmark suite.
- Input
- $17.84 / 1M
- Output
- $70.50 / 1M
- Context
- 400,000
- Avg score
- 86.0
- Open weights
- No
Gemini 3 Pro
Gemini 3 Pro is a frontier model from Google DeepMind. It offers a 2,000,000-token context window, costs $18.24 per million input tokens and $82.93 per million output tokens, and averages 86.1 across the index's benchmark suite.
- Input
- $18.24 / 1M
- Output
- $82.93 / 1M
- Context
- 2,000,000
- Avg score
- 86.1
- Open weights
- No
Specification comparison
| Spec | Claude Sonnet 4.5 | Gemini 3 Pro | Edge |
|---|---|---|---|
| Input price / 1M | $17.84 | $18.24 | A |
| Output price / 1M | $70.50 | $82.93 | A |
| Context window | 400,000 | 2,000,000 | B |
| Max output | 128,000 | 8,192 | A |
| Average score | 86.0 | 86.1 | B |
| Arena Elo | 1478.2 | 1460.7 | A |
| Open weights | No | No | Tie |
Benchmark comparison
Claude Sonnet 4.5 wins 6, Gemini 3 Pro wins 6, and 0 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | Claude Sonnet 4.5 | Gemini 3 Pro | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 88.0 | 88.2 | 0.2 | Gemini 3 Pro |
| GPQA Diamond | 82.6 | 79.0 | 3.6 | Claude Sonnet 4.5 |
| SWE-bench Verified | 74.2 | 78.5 | 4.3 | Gemini 3 Pro |
| HumanEval | 92.7 | 91.8 | 0.9 | Claude Sonnet 4.5 |
| MATH-500 | 87.0 | 89.9 | 2.9 | Gemini 3 Pro |
| AIME 2025 | 86.3 | 84.3 | 2.0 | Claude Sonnet 4.5 |
| LiveCodeBench | 82.5 | 83.3 | 0.8 | Gemini 3 Pro |
| IFEval | 91.1 | 93.7 | 2.6 | Gemini 3 Pro |
| TruthfulQA | 87.2 | 88.8 | 1.6 | Gemini 3 Pro |
| HellaSwag | 93.0 | 91.3 | 1.7 | Claude Sonnet 4.5 |
| MMMU | 80.9 | 78.6 | 2.3 | Claude Sonnet 4.5 |
| Arena Elo | 1478.2 | 1460.7 | 17.5 | Claude Sonnet 4.5 |
Price analysis
On a blended 3:1 input-to-output basis, Claude Sonnet 4.5 costs about $31.00 per million tokens and Gemini 3 Pro costs about $34.41. Claude Sonnet 4.5 is roughly 10% cheaper than Gemini 3 Pro. At high volume, that gap compounds quickly, so price should carry real weight unless the quality difference is decisive.
Gemini 3 Pro has the larger context window at 2,000,000 tokens, compared with 400,000 for Claude Sonnet 4.5. That matters for long documents, large codebases and multi-step agent traces.
Verdict
Across 12 shared benchmarks, Claude Sonnet 4.5 wins 6, Gemini 3 Pro wins 6, and 0 are tied. On the index average, Gemini 3 Pro leads Claude Sonnet 4.5 by 0.1 points (86.1 versus 86.0).
The price picture favours Claude Sonnet 4.5. The context picture favours Gemini 3 Pro. 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 3 Pro for quality-sensitive work and Claude Sonnet 4.5 for high-volume, well-scoped tasks. Run both on a sample of your own traffic before locking in a choice.
Choose Claude Sonnet 4.5 if
- Unit cost matters and you want the cheaper blended price.
- You need the larger 128,000-token output limit.
Choose Gemini 3 Pro if
- You want the higher average benchmark score in this index.
- You need the larger 2,000,000-token context window.
FAQ
Is Claude Sonnet 4.5 better than Gemini 3 Pro?
On the index average, Gemini 3 Pro leads Claude Sonnet 4.5 by 0.1 points (86.1 versus 86.0). The better choice depends on price, context and your task. Claude Sonnet 4.5 wins 6 benchmarks, Gemini 3 Pro wins 6.
Which is cheaper, Claude Sonnet 4.5 or Gemini 3 Pro?
Claude Sonnet 4.5 is cheaper on a blended 3:1 basis at about $31.00 per million tokens, versus $34.41 for Gemini 3 Pro.
Which has the larger context window?
Gemini 3 Pro has the larger context window at 2,000,000 tokens. Claude Sonnet 4.5 has 400,000 tokens.
Are these models open weights?
Claude Sonnet 4.5 is proprietary; Gemini 3 Pro is proprietary.
Which should I choose for production?
If you need a single default, start with Gemini 3 Pro for quality-sensitive work and Claude Sonnet 4.5 for high-volume, well-scoped tasks. Run both on a sample of your own traffic before locking in a choice.