Claude Opus 4.5 Reasoning vs Gemini 3 Pro Pro: which model should you choose?
We compared Claude Opus 4.5 Reasoning and Gemini 3 Pro Pro on price, context window and 12 benchmarks. Claude Opus 4.5 Reasoning has the stronger average benchmark score; Gemini 3 Pro 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
Gemini 3 Pro Pro
Gemini 3 Pro Pro is a frontier model from Google DeepMind. It offers a 200,000-token context window, costs $19.80 per million input tokens and $108.61 per million output tokens, and averages 87.3 across the index's benchmark suite.
- Input
- $19.80 / 1M
- Output
- $108.61 / 1M
- Context
- 200,000
- Avg score
- 87.3
- Open weights
- No
Specification comparison
| Spec | Claude Opus 4.5 Reasoning | Gemini 3 Pro Pro | Edge |
|---|---|---|---|
| Input price / 1M | $20.91 | $19.80 | B |
| Output price / 1M | $108.13 | $108.61 | A |
| Context window | 2,000,000 | 200,000 | A |
| Max output | 16,384 | 8,192 | A |
| Average score | 88.2 | 87.3 | A |
| Arena Elo | 1497.5 | 1484.4 | A |
| Open weights | No | No | Tie |
Benchmark comparison
Claude Opus 4.5 Reasoning wins 9, Gemini 3 Pro Pro wins 2, and 1 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | Claude Opus 4.5 Reasoning | Gemini 3 Pro Pro | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 90.7 | 88.2 | 2.5 | Claude Opus 4.5 Reasoning |
| GPQA Diamond | 82.6 | 81.4 | 1.2 | Claude Opus 4.5 Reasoning |
| SWE-bench Verified | 79.5 | 75.7 | 3.8 | Claude Opus 4.5 Reasoning |
| HumanEval | 92.1 | 95.0 | 2.9 | Gemini 3 Pro Pro |
| MATH-500 | 91.6 | 91.6 | 0.0 | Tie |
| AIME 2025 | 88.9 | 88.0 | 0.9 | Claude Opus 4.5 Reasoning |
| LiveCodeBench | 81.8 | 83.1 | 1.3 | Gemini 3 Pro Pro |
| IFEval | 95.9 | 92.7 | 3.2 | Claude Opus 4.5 Reasoning |
| TruthfulQA | 89.0 | 87.6 | 1.4 | Claude Opus 4.5 Reasoning |
| HellaSwag | 93.8 | 93.6 | 0.2 | Claude Opus 4.5 Reasoning |
| MMMU | 84.6 | 83.2 | 1.4 | Claude Opus 4.5 Reasoning |
| Arena Elo | 1497.5 | 1484.4 | 13.1 | 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 Gemini 3 Pro Pro costs about $42.00. Gemini 3 Pro Pro is roughly 2% 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 200,000 for Gemini 3 Pro Pro. That matters for long documents, large codebases and multi-step agent traces.
Verdict
Across 12 shared benchmarks, Claude Opus 4.5 Reasoning wins 9, Gemini 3 Pro Pro wins 2, and 1 are tied. On the index average, Claude Opus 4.5 Reasoning leads Gemini 3 Pro Pro by 0.9 points (88.2 versus 87.3).
The price picture favours Gemini 3 Pro Pro. 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 Claude Opus 4.5 Reasoning for quality-sensitive work and Gemini 3 Pro Pro for high-volume, well-scoped tasks. Run both on a sample of your own traffic before locking in a choice.
Choose Claude Opus 4.5 Reasoning if
- You want the higher average benchmark score in this index.
- You need the larger 2,000,000-token context window.
- You need the larger 16,384-token output limit.
Choose Gemini 3 Pro Pro if
- Unit cost matters and you want the cheaper blended price.
FAQ
Is Claude Opus 4.5 Reasoning better than Gemini 3 Pro Pro?
On the index average, Claude Opus 4.5 Reasoning leads Gemini 3 Pro Pro by 0.9 points (88.2 versus 87.3). The better choice depends on price, context and your task. Claude Opus 4.5 Reasoning wins 9 benchmarks, Gemini 3 Pro Pro wins 2.
Which is cheaper, Claude Opus 4.5 Reasoning or Gemini 3 Pro Pro?
Gemini 3 Pro Pro is cheaper on a blended 3:1 basis at about $42.00 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. Gemini 3 Pro Pro has 200,000 tokens.
Are these models open weights?
Claude Opus 4.5 Reasoning is proprietary; Gemini 3 Pro Pro is proprietary.
Which should I choose for production?
If you need a single default, start with Claude Opus 4.5 Reasoning for quality-sensitive work and Gemini 3 Pro Pro for high-volume, well-scoped tasks. Run both on a sample of your own traffic before locking in a choice.