Gemini 3.1 Pro Preview vs Gemini 3.5 Flash
API pricing, context window and capabilities for Gemini 3.1 Pro Preview and Gemini 3.5 Flash, side by side. Prices are the cheapest listed serving route per 1M tokens, from LiteLLM and OpenRouter.
Verdict
computed from the published numbersGemini 3.5 Flash wins on price, on Terminal-Bench and on intelligence.
Price
Gemini 3.5 Flash
Terminal-Bench
Gemini 3.5 Flash
Intelligence
Gemini 3.5 Flash
Context window
Tied
Key takeaways
who wins on what, from the published numbersGemini 3.1 Pro Preview wins
No clear edge on the tracked metrics.
Gemini 3.5 Flash wins
- Cheaper input ($2.00 vs $1.50 /1M)
- Cheaper output ($12.00 vs $9.00 /1M)
- More serving providers (6 vs 7)
Cheaper overall
Gemini 3.5 Flash
$1.50 + $9.00 /1M
Larger context
Tied
More providers
Gemini 3.5 Flash
7 providers
Pricing & specs
cheapest listed route · per 1M tokensOn-demand listed rates, OpenRouter routed quotes and Vercel reseller quotes. Enterprise commitments can be materially lower.
| Gemini 3.1 Pro Preview | Gemini 3.5 Flash | |
|---|---|---|
| Input $/1M | $2.00via Google | $1.50via Google best |
| Output $/1M | $12.00via Google | $9.00via Google best |
| Context window | 1M | 1M |
| Max output | 66K | 66K |
| Serving providers | 6 | 7 best |
| Date | Released Feb 19, 2026 | Released May 22, 2026 |
Benchmarks
Benchmark scores, side by side| Gemini 3.1 Pro Preview | Gemini 3.5 Flash | |
|---|---|---|
| Intelligence | 29.7 | 32.6 best |
| Terminal-Bench | 74% | 79% best |
| GPQA Diamond | 94% best | 92% |
| Output speed | 140 t/s | 197 t/s best |
| Latency (TTFT) | 26.52s | 17.14s best |
Cost calculator
choose a serving route for each sideInput tokens / month
Output tokens / month
Gemini 3.1 Pro Preview
via Google
$22
Gemini 3.5 Flash
via OpenRouter
$17
Capabilities
feature support, side by side| Feature | Gemini 3.1 Pro Preview | Gemini 3.5 Flash |
|---|---|---|
| Vision | ✓ | ✓ |
| Tool use | ✓ | ✓ |
| Reasoning | ✓ | ✓ |
| Audio | ✓ | ✓ |
| Prompt caching | ✓ | ✓ |
| Structured output | ✓ | ✓ |
| Web search | ✓ | ✓ |
Related comparisons
Frequently asked questions
Which is cheaper, Gemini 3.1 Pro Preview or Gemini 3.5 Flash?
Gemini 3.5 Flash is cheaper for input ($2.00 vs $1.50 per 1M tokens) from Google. Gemini 3.5 Flash is cheaper for output ($12.00 vs $9.00 per 1M tokens) from Google.
What is the context window difference between Gemini 3.1 Pro Preview and Gemini 3.5 Flash?
Both Gemini 3.1 Pro Preview and Gemini 3.5 Flash have about a 1M-token context window.
How do Gemini 3.1 Pro Preview and Gemini 3.5 Flash compare on benchmarks?
On the tracked benchmarks, Gemini 3.5 Flash leads on Terminal-Bench, and Gemini 3.5 Flash leads on intelligence.
Listed prices from LiteLLM, OpenRouter and Vercel · last checked Oct 14, 2026
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