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 serving route per 1M tokens, verified against LiteLLM and OpenRouter.
Verdict
computed from the published numbersGemini 3.5 Flash wins on price, on coding and on intelligence.
Price
Gemini 3.5 Flash
Coding
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
- More serving providers (4 vs 3)
Gemini 3.5 Flash wins
- Cheaper input ($2.00 vs $1.50 /1M)
- Cheaper output ($12.00 vs $9.00 /1M)
Cheaper overall
Gemini 3.5 Flash
$1.50 + $9.00 /1M
Larger context
Tied
More providers
Gemini 3.1 Pro Preview
4 providers
Pricing & specs
cheapest serving route · per 1M tokens| Gemini 3.1 Pro Preview | Gemini 3.5 Flash | |
|---|---|---|
| Input $/1M | $2.00 | $1.50 best |
| Output $/1M | $12.00 | $9.00 best |
| Context window | 1M | 1M |
| Max output | 66K | 66K |
| Serving providers | 4 best | 3 |
| Released | 2026-02-19 | 2026-05-22 |
Benchmarks
Artificial Analysis indices, side by side| Gemini 3.1 Pro Preview | Gemini 3.5 Flash | |
|---|---|---|
| Intelligence | 46.5 | 50.2 best |
| Coding | 68.8 | 70.1 best |
| GPQA Diamond | 94% best | 92% |
| Output speed | 154 t/s | 188 t/s best |
| Latency (TTFT) | 34.98s | 18.79s best |
Cost calculator
choose a serving route for each sideInput tokens / month
Output tokens / month
Gemini 3.1 Pro Preview
via Vertex AI
$22
Gemini 3.5 Flash
via Vertex AI
$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). Gemini 3.5 Flash is cheaper for output ($12.00 vs $9.00 per 1M tokens).
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 Artificial Analysis indices, Gemini 3.5 Flash leads on coding, and Gemini 3.5 Flash leads on intelligence.
Pricing verified against LiteLLM + OpenRouter + provider pages · refreshed daily
Every weekday
AI moves fast. Here's your debrief.
News, analysis, tools, and more.
For people who build with AI