# Gemini 3.5 Flash Lite vs Gemini 3.1 Flash Lite

> Markdown mirror of https://router.one/models/compare/gemini-3-5-flash-lite-vs-gemini-3-1-flash-lite for AI assistants and crawlers. Router One is a unified, OpenAI-compatible LLM API gateway.

Gemini 3.1 Flash Lite is the lower-priced of the two on Router One — about 37% less on a 1M-input + 1M-output mix. Both carry a 1.05M context window. Both answer on /v1/chat/completions.

Gemini 3.5 Flash Lite and Gemini 3.1 Flash Lite compared on current per-token rates, context window, and capabilities — both callable through one OpenAI-compatible endpoint with per-request cost traces.

## Gemini 3.5 Flash Lite vs Gemini 3.1 Flash Lite: rates, context window, and capabilities

| Spec | Gemini 3.5 Flash Lite | Gemini 3.1 Flash Lite |
| --- | --- | --- |
| Input / 1M tokens | $0.30 | $0.25 |
| Output / 1M tokens | $2.50 | $1.50 |
| Cached input / 1M tokens | $0.30 | $0.25 |
| Context window | 1.05M | 1.05M |
| Capabilities | Chat, Streaming, Tool calling, Vision | Chat, Streaming, Tool calling, Vision |
| Subscription plans | Not in any plan — wallet | Not in any plan — wallet |
| Detail page | [Gemini 3.5 Flash Lite](https://router.one/models/gemini-3-5-flash-lite) | [Gemini 3.1 Flash Lite](https://router.one/models/gemini-3-1-flash-lite) |

## What does 1M tokens cost on Gemini 3.5 Flash Lite vs Gemini 3.1 Flash Lite?

For a workload of 1M input plus 1M output tokens at current rates: Gemini 3.5 Flash Lite comes to $2.80, Gemini 3.1 Flash Lite comes to $1.75 — Gemini 3.1 Flash Lite is about 37% cheaper on this mix. Real workloads skew heavily toward input tokens, so weigh the input rate by your own ratio; the cached-input row above is the posted catalog rate for that model.

## Switch between Gemini 3.5 Flash Lite and Gemini 3.1 Flash Lite

The API key, base URL and endpoint stay the same — Router One serves both on /v1/chat/completions — but per Google's guide to Gemini 3.6 Flash and 3.5 Flash-Lite (checked 2026-10-09), starting with those models the Gemini API ignores temperature, top_p and top_k and rejects a request whose last turn is a prefilled model turn, and Gemini 3.5 Flash Lite's default thinking level is minimal; Gemini 3.1 Flash Lite predates these changes. Move tone and format rules into the system message before you switch, and compare both on your own prompts.

`compare.sh`

```bash
curl https://api.router.one/v1/chat/completions \
  -H "Authorization: Bearer sk-your-router-one-key" \
  -H "Content-Type: application/json" \
  -d '{"model": "google/gemini-3.5-flash-lite", "messages": [{"role": "user", "content": "Hello"}]}'

# Same request, other model — change one string:
#   "model": "google/gemini-3.1-flash-lite"
```

## FAQ

### Is Gemini 3.5 Flash Lite cheaper than Gemini 3.1 Flash Lite?

Input: Gemini 3.5 Flash Lite $0.30 vs Gemini 3.1 Flash Lite $0.25 / 1M tokens; Gemini 3.1 Flash Lite has the lower rate. Output: Gemini 3.5 Flash Lite $2.50 vs Gemini 3.1 Flash Lite $1.50 / 1M tokens; Gemini 3.1 Flash Lite has the lower rate. Total cost depends on the workload's input, output and cache usage. Rates change; the /models page is the live source of truth.

### Is Gemini 3.5 Flash Lite or Gemini 3.1 Flash Lite included in a Router One subscription?

Neither Gemini 3.5 Flash Lite nor Gemini 3.1 Flash Lite is in a Router One plan, so every call to either bills the wallet per token.

### Can I switch between Gemini 3.5 Flash Lite and Gemini 3.1 Flash Lite without changing code?

The API key, base URL and endpoint stay the same — Router One serves both on /v1/chat/completions — but per Google's guide to Gemini 3.6 Flash and 3.5 Flash-Lite (checked 2026-10-09), starting with those models the Gemini API ignores temperature, top_p and top_k and rejects a request whose last turn is a prefilled model turn, and Gemini 3.5 Flash Lite's default thinking level is minimal; Gemini 3.1 Flash Lite predates these changes. Move tone and format rules into the system message before you switch, and compare both on your own prompts.

### Where do these numbers come from?

Specs and prices on this page render from the live Router One catalog — the same data as the /models page — and refresh with it. Pricing methodology is documented on /pricing-methodology. Rates on this page were read from the live catalog on 2026-10-09 (UTC) and refresh within the hour.

## More comparisons

- [Gemini 3.5 Flash Lite vs Gemini 3.5 Flash](https://router.one/models/compare/gemini-3-5-flash-lite-vs-gemini-3-5-flash)
- [Grok 4.7 vs Gemini 3.8 Flash](https://router.one/models/compare/grok-4-7-vs-gemini-3-8-flash)
- [Gemini 3.8 Flash vs GPT-5.6 Terra](https://router.one/models/compare/gemini-3-8-flash-vs-gpt-5-6-terra)
- [Claude Haiku 4.5 vs Gemini 3.5 Flash](https://router.one/models/compare/claude-haiku-4-5-vs-gemini-3-5-flash)

## See also

- Canonical page: https://router.one/models/compare/gemini-3-5-flash-lite-vs-gemini-3-1-flash-lite
- All model comparisons: https://router.one/models/compare
- All models & prices: https://router.one/models (markdown: https://router.one/models.md)
- Pricing: https://router.one/pricing
- Gemini API in China: https://router.one/gemini-api-china
- Cost calculator: https://router.one/llm-cost-calculator
- Pricing methodology: https://router.one/pricing-methodology