AI model comparison
Gemini 3.5 Flash vs Gemini 3.1 Pro Preview
Pricing, context window, benchmarks, and features compared side by side. Or skip the guesswork and send one prompt to both.
Gemini 3.5 Flash
Gemini 3.5 Flash is Google's high-efficiency multimodal model, bringing near-Pro level coding and reasoning at Flash-tier cost and speed.
- Input / 1M
- $1.50
- Output / 1M
- $9
- Context
- 1.05M
Gemini 3.1 Pro Preview
Gemini 3.1 Pro Preview is Google’s frontier reasoning model, delivering enhanced software engineering performance, improved agentic reliability, and more efficient token usage across complex workflows.
- Input / 1M
- $2
- Output / 1M
- $12
- Context
- 1.05M
At a glance
Quick verdict
How the two models stack up on the things people ask about most.
Lower price
Gemini 3.5 Flash
1.3x cheaper for a typical chat
Higher intelligence score
Gemini 3.5 Flash
33.6 vs 29.7 on Artificial Analysis
Larger context window
Tie
1.05M vs 1.05M tokens
Newer release
Gemini 3.5 Flash
Released May 19, 2026
Benchmarks
Benchmark scores
Independent scores from Artificial Analysis. Higher is better.
Intelligence index
Gemini 3.5 Flash33.6Gemini 3.1 Pro Preview29.7Coding index
Gemini 3.5 FlashNot availableGemini 3.1 Pro Preview68.8Agentic index
Gemini 3.5 FlashNot availableGemini 3.1 Pro Preview8.2Pricing
Gemini 3.5 Flash vs Gemini 3.1 Pro Preview API pricing
Per-token API rates. Cheaper option highlighted.
| Metric | Gemini 3.5 Flash | Gemini 3.1 Pro Preview |
|---|---|---|
| Input tokensPer 1M tokens | $1.50 | $2 |
| Output tokensPer 1M tokens | $9 | $12 |
| Cached input (read)Per 1M tokens | $0.15 | $0.20 |
| Cache writePer 1M tokens | $0.08 | $0.38 |
| Long-context pricingPer 1M tokens, for very long prompts | Same rate at any length | $4 in / $18 out above 200K |
| Web searchPer request | $0.014 | $0.014 |
What it costs in practice
Estimated cost per 1,000 requests at standard rates. Coding and long-document figures also show the cost when the input is already cached.
Chat message
2K in, 500 out
Gemini 3.5 Flash$7.50Gemini 3.1 Pro Preview$10Coding task
30K in, 4K out
Gemini 3.5 Flash$81$40.50 cachedGemini 3.1 Pro Preview$108$54 cachedLong document summary
150K in, 2K out
Gemini 3.5 Flash$243$40.50 cachedGemini 3.1 Pro Preview$324$54 cachedSpecs
Context window and capabilities
How much each model can read, how much it can write, and what it accepts as input.
| Metric | Gemini 3.5 Flash | Gemini 3.1 Pro Preview |
|---|---|---|
| Context window | 1.05M tokens | 1.05M tokens |
| Max output | 66K tokens | 66K tokens |
| Input types | Audio, File, Image, Text, Video | Audio, File, Image, Text, Video |
| Output types | Text | Text |
| Reasoning effort levels | High, Medium, Low, Minimal | High, Medium, Low |
| Default reasoning effort | Medium | Medium |
| Release date | May 19, 2026 | February 19, 2026 |
Features
Supported features
API features available for each model.
| Metric | Gemini 3.5 Flash | Gemini 3.1 Pro Preview |
|---|---|---|
| Tool calling | Supported | Supported |
| Structured outputs | Supported | Supported |
| JSON mode | Supported | Supported |
| Reasoning | Supported | Supported |
| Temperature | Supported | Supported |
| Stop sequences | Supported | Supported |
| Deterministic seed | Supported | Supported |
| Verbosity control | Not supported | Not supported |
Keep exploring
More on these models
Other head-to-heads, the full model page, and the alternatives list for each model.
Gemini 3.5 FlashView full model details- Gemini 3.5 Flash vs Gemini 3.8 Flash
- Gemini 3.5 Flash vs Claude Sonnet 5
- Gemini 3.5 Flash vs DeepSeek V4 Flash 0731
- Gemini 3.5 Flash vs Gemini 3.6 Flash
- Gemini 3.5 Flash vs GLM 5.2
- Gemini 3.5 Flash vs Qwen3.8 27B
- Gemini 3.5 Flash vs Muse Spark 1.1
- Gemini 3.5 Flash vs GPT-5.3-Codex
- Gemini 3.5 Flash vs Claude Opus 4.6
- Gemini 3.5 Flash vs GPT-5.2
- Gemini 3.5 Flash vs Claude Sonnet 4.6
Gemini 3.1 Pro PreviewView full model details- Gemini 3.1 Pro Preview vs Claude Opus 5.5
- Gemini 3.1 Pro Preview vs GPT-6 Astra
- Gemini 3.1 Pro Preview vs GLM 5.2
- Gemini 3.1 Pro Preview vs GPT-5.3-Codex
- Gemini 3.1 Pro Preview vs Gemini 3 Flash Preview
- Gemini 3.1 Pro Preview vs Claude Opus 4.6
- Gemini 3.1 Pro Preview vs GPT-5.2
- Gemini 3.1 Pro Preview vs Claude Sonnet 4.6
- Gemini 3.1 Pro Preview vs Qwen3.7 Max
- Gemini 3.1 Pro Preview vs Claude Opus 4.5
- Gemini 3.1 Pro Preview vs GPT-5.2-Codex
Our take
Gemini 3.5 Flash is 1.3x cheaper for a typical chat. Gemini 3.5 Flash scores higher on the Artificial Analysis Intelligence Index (33.6 vs 29.7). The right pick depends on your workload, so the quickest way to settle it is to send the same prompt to both and compare.
FAQ
Frequently asked questions
Is Gemini 3.5 Flash or Gemini 3.1 Pro Preview cheaper?
Gemini 3.5 Flash is cheaper for a typical chat (2K input tokens and 500 output tokens). Gemini 3.5 Flash costs $1.50 per 1M input tokens and $9 per 1M output tokens, while Gemini 3.1 Pro Preview costs $2 per 1M input tokens and $12 per 1M output tokens.
Which has a bigger context window, Gemini 3.5 Flash or Gemini 3.1 Pro Preview?
Gemini 3.5 Flash supports up to 1.05M tokens of context, compared with 1.05M for Gemini 3.1 Pro Preview.
Is Gemini 3.5 Flash smarter than Gemini 3.1 Pro Preview?
On the Artificial Analysis Intelligence Index, Gemini 3.5 Flash scores 33.6 and Gemini 3.1 Pro Preview scores 29.7, putting Gemini 3.5 Flash ahead. Benchmarks don't capture everything, so the best test is running your own prompts through both.
Can I use Gemini 3.5 Flash and Gemini 3.1 Pro Preview at the same time?
Yes. Shortcut Chat sends one prompt to multiple models at once, so you can see Gemini 3.5 Flash and Gemini 3.1 Pro Preview answer side by side and keep the better response.
Why choose? Ask both.
Send one prompt to Gemini 3.5 Flash and Gemini 3.1 Pro Preview at the same time. Compare the answers side by side and keep the best one.