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Gemini 3.1 Pro vs Gemini 2.5 Flash
A detailed comparison of Gemini 3.1 Pro (Google) and Gemini 2.5 Flash (Google) across pricing, performance, and features.
Pricing Comparison
| Metric | Gemini 3.1 Pro | Gemini 2.5 Flash | Difference |
|---|---|---|---|
| Input / 1M tokens | $2.00 | $0.15 | -93% |
| Output / 1M tokens | $12.00 | $0.60 | -95% |
| Context window | 1M | 1M | — |
| Max output | 64K | 65.536K | — |
Benchmark Comparison
| Benchmark | Gemini 3.1 Pro | Gemini 2.5 Flash |
|---|---|---|
| MMLU-Pro | 91% | 76% |
| HumanEval | 95% | 89.5% |
| GPQA | 94.3% | — |
Capabilities
| Capability | Gemini 3.1 Pro | Gemini 2.5 Flash |
|---|---|---|
| audio | ✓ | ✗ |
| code | ✓ | ✓ |
| reasoning | ✓ | ✓ |
| text | ✓ | ✓ |
| tool-use | ✓ | ✓ |
| vision | ✓ | ✓ |
Gemini 3.1 Pro Strengths
- ✓#1 on 12 of 18 tracked benchmarks
- ✓94.3% GPQA Diamond — highest of any model
- ✓Same price as Gemini 3 Pro (free upgrade)
- ✓1M context with configurable thinking levels
Gemini 3.1 Pro Weaknesses
- ✗Still in preview
- ✗Context-tiered pricing ($4/$18 above 200K)
Gemini 2.5 Flash Strengths
- ✓One of the cheapest models available
- ✓1M context at budget pricing
- ✓Free tier available
Gemini 2.5 Flash Weaknesses
- ✗Weaker than Flash 3 on most benchmarks
- ✗Output quality inconsistent on edge cases
Quick Verdict
Best value: Gemini 2.5 Flash is the more affordable option at $0.15/$0.6 per 1M tokens.
Higher benchmarks: Gemini 3.1 Pro scores higher on average across available benchmarks (93.4% avg).
Choose Gemini 2.5 Flash if cost matters most. Choose Gemini 3.1 Pro if you need the best possible quality for complex tasks.