Gemini 3.5 Flash vs Gemini 3.1 Flash-Lite
Google's Gemini 3.5 Flash and Google's Gemini 3.1 Flash-Lite both target production language workloads, but they price and behave differently. Here is the side-by-side.
Pricing checked against provider documentation on . How we verify
The short answer
Gemini 3.1 Flash-Lite is the cheaper option — roughly 6.0x less on a blended workload, and it suits ultra-cheap high-volume tasks. Gemini 3.5 Flash justifies its premium when you need agentic loops and sub-agent fleets. Only Gemini 3.5 Flash does native reasoning, which matters for multi-step tasks but adds billable thinking tokens.
Google • Gemini 3.5
$1.50 / $9.00
/ 1M tokens (input / output)
Google's most capable Flash model, tuned for the agentic era: sub-agent deployment, multi-step workflows, and rapid coding iterations at scale. Supports search grounding, function calling, structured outputs, and computer use in preview. Note that it is pricier than the Gemini 3 Flash preview it replaced.
Google • Gemini 3.1
$0.25 / $1.50
/ 1M tokens (input / output)
Google's efficiency tier and a long-term stable target, priced for workloads measured in millions of calls rather than thousands. It gives up the deeper reasoning of 3.5 Flash, so it suits mechanical tasks — classification, extraction, moderation — where a million tokens of context still helps but chain-of-thought does not.
Input price
Gemini 3.1 Flash-Lite is 83% cheaper than Gemini 3.5 Flash on input tokens.
Output price
Gemini 3.1 Flash-Lite is 83% cheaper than Gemini 3.5 Flash on output tokens — usually the side that dominates the bill.
Monthly cost at three workload sizes
Standard (non-batch, non-cached) rates. Reasoning models will exceed these figures because thinking tokens bill as output.
| Workload | Gemini 3.5 Flash | Gemini 3.1 Flash-Lite | Difference |
|---|---|---|---|
| Light — 1M in / 200K out | $3 | $1 | $3 |
| Moderate — 10M in / 2M out | $33 | $6 | $28 |
| Heavy — 100M in / 20M out | $330 | $55 | $275 |
Specification comparison
| Attribute | Gemini 3.5 Flash | Gemini 3.1 Flash-Lite |
|---|---|---|
| Input (/ 1M tokens) | $1.50 | $0.25 |
| Output (/ 1M tokens) | $9.00 | $1.50 |
| Cached input | — | — |
| Context window | 1,048,576 tokens | 1,048,576 tokens |
| Max output | 65,536 tokens | 65,536 tokens |
| Native reasoning | Yes | No |
| Knowledge cutoff | 2025-01 | 2025-01 |
| Relative latency | low | low |
| Open weights | No | No |
| API model ID | gemini-3.5-flash | gemini-3.1-flash-lite |
| Status | stable | stable |
Gemini 3.5 Flash: Flat rate at any context length, unlike Gemini 3.1 Pro's 200K cliff.
Choose Gemini 3.5 Flash if…
- Sub-agent fleets and orchestration
- Fast coding iteration loops
- Search-grounded answers
- Multimodal ingestion at scale
Choose Gemini 3.1 Flash-Lite if…
- Content moderation at volume
- Classification and routing
- Lightweight summarization
- Cheap long-context retrieval
Frequently asked
Is Gemini 3.5 Flash or Gemini 3.1 Flash-Lite cheaper?
Gemini 3.1 Flash-Lite is cheaper. On a blended 3:1 input-to-output workload it costs about 6.0x less than Gemini 3.5 Flash.
Which has the larger context window, Gemini 3.5 Flash or Gemini 3.1 Flash-Lite?
Both accept up to 1.05M tokens, so context is not a differentiator here.
Should I use Gemini 3.5 Flash or Gemini 3.1 Flash-Lite?
Pick Gemini 3.5 Flash for agentic loops and sub-agent fleets. Pick Gemini 3.1 Flash-Lite for ultra-cheap high-volume tasks. If cost dominates the decision, Gemini 3.1 Flash-Lite wins; if you need the capability ceiling, benchmark both on your own evals before committing.