Model comparison
Gemini 3.1 Pro Preview vs Gemini 3.5 Flash
Compare Gemini 3.1 Pro Preview vs Gemini 3.5 Flash API pricing: input/output token costs, cache pricing, context windows, workload estimates, and routing fit.
Gemini 3.1 Pro Preview
gemini · gemini-3.1-pro-preview
- Input
- $2
- Output
- $12
- Context
- 1M
Gemini 3.5 Flash
gemini · gemini-3.5-flash
- Input
- $1.5
- Output
- $9
- Context
- 1M
Quick take
Gemini 3.5 Flash has the lower input price at $1.5 per 1M input tokens. Gemini 3.5 Flash is cheaper for the example blended workload below. Gemini 3.1 Pro Preview has the larger context window at 1M tokens.
Choose Gemini 3.1 Pro Preview if...
- Gemini 3.1 Pro Preview is a reasonable pick when its provider, latency, or integration path fits your stack better.
Choose Gemini 3.5 Flash if...
- Gemini 3.5 Flash is the better default for cost-sensitive traffic and repeated high-volume calls.
Example workload cost
Estimates use input tokens plus 20% output tokens. They exclude provider discounts, cache hits, and tool/search surcharges.
| Workload | Gemini 3.1 Pro Preview | Gemini 3.5 Flash | Cheaper |
|---|---|---|---|
| 1M input + 200K output | $4.40 | $3.30 | Gemini 3.5 Flash |
| 10M input + 2M output | $44.00 | $33.00 | Gemini 3.5 Flash |
| 100M input + 20M output | $440.00 | $330.00 | Gemini 3.5 Flash |
Context, output, and capability fit
Gemini 3.1 Pro Preview provides the larger context window. Check max output separately when the task needs long reports, code generation, or full-document rewrites.
- Gemini 3.1 Pro Preview max output
- 65.5K
- Gemini 3.5 Flash max output
- 65.5K
- Gemini 3.1 Pro Preview features
- prompt caching, function calling, vision
- Gemini 3.5 Flash features
- prompt caching, function calling, vision
Risk notes for Gemini 3.1 Pro Preview
- Preview or beta model: verify availability and pricing before production rollout.
Risk notes for Gemini 3.5 Flash
- No major capability risk is flagged in this snapshot, but provider pages should still be verified before production routing.
Routing tags
frontierpreviewreasoninglong-contextmultimodalenterprise-ragragfastcache-friendlystablebudget