Claude Haiku 4.5 Reasoning vs Gemini 2.5 Pro: which model should you choose?
We compared Claude Haiku 4.5 Reasoning and Gemini 2.5 Pro on price, context window and 12 benchmarks. Gemini 2.5 Pro has the stronger average benchmark score; Gemini 2.5 Pro is cheaper on a blended 3:1 basis.
Claude Haiku 4.5 Reasoning
Claude Haiku 4.5 Reasoning is a multimodal model from Anthropic. It offers a 128,000-token context window, costs $15.11 per million input tokens and $70.05 per million output tokens, and averages 81.4 across the index's benchmark suite.
- Input
- $15.11 / 1M
- Output
- $70.05 / 1M
- Context
- 128,000
- Avg score
- 81.4
- Open weights
- No
Gemini 2.5 Pro
Gemini 2.5 Pro is a multimodal model from Google DeepMind. It offers a 200,000-token context window, costs $15.20 per million input tokens and $57.83 per million output tokens, and averages 81.6 across the index's benchmark suite.
- Input
- $15.20 / 1M
- Output
- $57.83 / 1M
- Context
- 200,000
- Avg score
- 81.6
- Open weights
- No
Specification comparison
| Spec | Claude Haiku 4.5 Reasoning | Gemini 2.5 Pro | Edge |
|---|---|---|---|
| Input price / 1M | $15.11 | $15.20 | A |
| Output price / 1M | $70.05 | $57.83 | B |
| Context window | 128,000 | 200,000 | B |
| Max output | 128,000 | 16,384 | A |
| Average score | 81.4 | 81.6 | B |
| Arena Elo | 1444.2 | 1455.0 | B |
| Open weights | No | No | Tie |
Benchmark comparison
Claude Haiku 4.5 Reasoning wins 4, Gemini 2.5 Pro wins 8, and 0 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | Claude Haiku 4.5 Reasoning | Gemini 2.5 Pro | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 83.4 | 83.6 | 0.2 | Gemini 2.5 Pro |
| GPQA Diamond | 74.6 | 76.5 | 1.9 | Gemini 2.5 Pro |
| SWE-bench Verified | 69.6 | 70.2 | 0.6 | Gemini 2.5 Pro |
| HumanEval | 88.7 | 87.7 | 1.0 | Claude Haiku 4.5 Reasoning |
| MATH-500 | 85.8 | 86.8 | 1.0 | Gemini 2.5 Pro |
| AIME 2025 | 79.0 | 76.1 | 2.9 | Claude Haiku 4.5 Reasoning |
| LiveCodeBench | 73.8 | 76.2 | 2.4 | Gemini 2.5 Pro |
| IFEval | 89.9 | 87.6 | 2.3 | Claude Haiku 4.5 Reasoning |
| TruthfulQA | 82.5 | 82.8 | 0.3 | Gemini 2.5 Pro |
| HellaSwag | 90.9 | 89.7 | 1.2 | Claude Haiku 4.5 Reasoning |
| MMMU | 76.7 | 80.5 | 3.8 | Gemini 2.5 Pro |
| Arena Elo | 1444.2 | 1455.0 | 10.8 | Gemini 2.5 Pro |
Price analysis
On a blended 3:1 input-to-output basis, Claude Haiku 4.5 Reasoning costs about $28.84 per million tokens and Gemini 2.5 Pro costs about $25.86. Gemini 2.5 Pro is roughly 10% cheaper than Claude Haiku 4.5 Reasoning. At high volume, that gap compounds quickly, so price should carry real weight unless the quality difference is decisive.
Gemini 2.5 Pro has the larger context window at 200,000 tokens, compared with 128,000 for Claude Haiku 4.5 Reasoning. That matters for long documents, large codebases and multi-step agent traces.
Verdict
Across 12 shared benchmarks, Claude Haiku 4.5 Reasoning wins 4, Gemini 2.5 Pro wins 8, and 0 are tied. On the index average, Gemini 2.5 Pro leads Claude Haiku 4.5 Reasoning by 0.2 points (81.6 versus 81.4).
The price picture favours Gemini 2.5 Pro. The context picture favours Gemini 2.5 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 2.5 Pro for quality-sensitive work, and check whether its price holds at your expected volume before committing.
Choose Claude Haiku 4.5 Reasoning if
- You need the larger 128,000-token output limit.
Choose Gemini 2.5 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 200,000-token context window.
FAQ
Is Claude Haiku 4.5 Reasoning better than Gemini 2.5 Pro?
On the index average, Gemini 2.5 Pro leads Claude Haiku 4.5 Reasoning by 0.2 points (81.6 versus 81.4). The better choice depends on price, context and your task. Claude Haiku 4.5 Reasoning wins 4 benchmarks, Gemini 2.5 Pro wins 8.
Which is cheaper, Claude Haiku 4.5 Reasoning or Gemini 2.5 Pro?
Gemini 2.5 Pro is cheaper on a blended 3:1 basis at about $25.86 per million tokens, versus $28.84 for Claude Haiku 4.5 Reasoning.
Which has the larger context window?
Gemini 2.5 Pro has the larger context window at 200,000 tokens. Claude Haiku 4.5 Reasoning has 128,000 tokens.
Are these models open weights?
Claude Haiku 4.5 Reasoning is proprietary; Gemini 2.5 Pro is proprietary.
Which should I choose for production?
If you need a single default, start with Gemini 2.5 Pro for quality-sensitive work, and check whether its price holds at your expected volume before committing.