Claude Haiku 4.5 Reasoning vs Gemini 3 Flash: which model should you choose?
We compared Claude Haiku 4.5 Reasoning and Gemini 3 Flash on price, context window and 12 benchmarks. Gemini 3 Flash has the stronger average benchmark score; Claude Haiku 4.5 Reasoning 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 3 Flash
Gemini 3 Flash is a multimodal model from Google DeepMind. It offers a 128,000-token context window, costs $15.67 per million input tokens and $70.15 per million output tokens, and averages 83.6 across the index's benchmark suite.
- Input
- $15.67 / 1M
- Output
- $70.15 / 1M
- Context
- 128,000
- Avg score
- 83.6
- Open weights
- No
Specification comparison
| Spec | Claude Haiku 4.5 Reasoning | Gemini 3 Flash | Edge |
|---|---|---|---|
| Input price / 1M | $15.11 | $15.67 | A |
| Output price / 1M | $70.05 | $70.15 | A |
| Context window | 128,000 | 128,000 | Tie |
| Max output | 128,000 | 65,536 | A |
| Average score | 81.4 | 83.6 | B |
| Arena Elo | 1444.2 | 1450.7 | B |
| Open weights | No | No | Tie |
Benchmark comparison
Claude Haiku 4.5 Reasoning wins 2, Gemini 3 Flash wins 10, and 0 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | Claude Haiku 4.5 Reasoning | Gemini 3 Flash | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 83.4 | 83.7 | 0.3 | Gemini 3 Flash |
| GPQA Diamond | 74.6 | 80.3 | 5.7 | Gemini 3 Flash |
| SWE-bench Verified | 69.6 | 72.5 | 2.9 | Gemini 3 Flash |
| HumanEval | 88.7 | 86.2 | 2.5 | Claude Haiku 4.5 Reasoning |
| MATH-500 | 85.8 | 89.0 | 3.2 | Gemini 3 Flash |
| AIME 2025 | 79.0 | 84.5 | 5.5 | Gemini 3 Flash |
| LiveCodeBench | 73.8 | 79.3 | 5.5 | Gemini 3 Flash |
| IFEval | 89.9 | 91.0 | 1.1 | Gemini 3 Flash |
| TruthfulQA | 82.5 | 84.8 | 2.3 | Gemini 3 Flash |
| HellaSwag | 90.9 | 89.8 | 1.1 | Claude Haiku 4.5 Reasoning |
| MMMU | 76.7 | 78.2 | 1.5 | Gemini 3 Flash |
| Arena Elo | 1444.2 | 1450.7 | 6.5 | Gemini 3 Flash |
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 3 Flash costs about $29.29. Claude Haiku 4.5 Reasoning is roughly 2% cheaper than Gemini 3 Flash. 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 Haiku 4.5 Reasoning wins 2, Gemini 3 Flash wins 10, and 0 are tied. On the index average, Gemini 3 Flash leads Claude Haiku 4.5 Reasoning by 2.2 points (83.6 versus 81.4).
The price picture favours Claude Haiku 4.5 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 3 Flash for quality-sensitive work and Claude Haiku 4.5 Reasoning for high-volume, well-scoped tasks. Run both on a sample of your own traffic before locking in a choice.
Choose Claude Haiku 4.5 Reasoning if
- Unit cost matters and you want the cheaper blended price.
- You need the larger 128,000-token output limit.
Choose Gemini 3 Flash if
- You want the higher average benchmark score in this index.
FAQ
Is Claude Haiku 4.5 Reasoning better than Gemini 3 Flash?
On the index average, Gemini 3 Flash leads Claude Haiku 4.5 Reasoning by 2.2 points (83.6 versus 81.4). The better choice depends on price, context and your task. Claude Haiku 4.5 Reasoning wins 2 benchmarks, Gemini 3 Flash wins 10.
Which is cheaper, Claude Haiku 4.5 Reasoning or Gemini 3 Flash?
Claude Haiku 4.5 Reasoning is cheaper on a blended 3:1 basis at about $28.84 per million tokens, versus $29.29 for Gemini 3 Flash.
Which has the larger context window?
Both models list a 128,000-token context window.
Are these models open weights?
Claude Haiku 4.5 Reasoning is proprietary; Gemini 3 Flash is proprietary.
Which should I choose for production?
If you need a single default, start with Gemini 3 Flash for quality-sensitive work and Claude Haiku 4.5 Reasoning for high-volume, well-scoped tasks. Run both on a sample of your own traffic before locking in a choice.