Gemini 2.5 Flash vs Gemini 3.1 Flash-Lite
Gemini 2.5 Flash (2025) and Gemini 3.1 Flash-Lite (2026) are general-purpose language models from Google DeepMind. Gemini 2.5 Flash ships a 1M-token context window, while Gemini 3.1 Flash-Lite ships a 1M-token context window. On Chatbot Arena, Gemini 3.1 Flash-Lite leads by 112 pts. On pricing, Gemini 3.1 Flash-Lite costs $0.25/1M input tokens versus $0.3/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit.
Pick Gemini 3.1 Flash-Lite for general evaluation; Gemini 2.5 Flash is better when coding workflow support matters more.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-06-17 | 2026-05-07 |
| Context window | 1M | 1M |
| Parameters | — | — |
| Architecture | decoder only | decoder only |
| License | Proprietary | Proprietary |
| Knowledge cutoff | 2025-01 | 2025-01 |
Pricing and availability
| Pricing attribute | Gemini 2.5 Flash | Gemini 3.1 Flash-Lite |
|---|---|---|
| Input price | $0.3/1M tokens | $0.25/1M tokens |
| Output price | $2.5/1M tokens | $1.5/1M tokens |
| Providers |
Capabilities
| Capability | Gemini 2.5 Flash | Gemini 3.1 Flash-Lite |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | No | No |
| Function calling | Yes | Yes |
| Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | Yes | Yes |
Benchmarks
| Benchmark | Gemini 2.5 Flash | Gemini 3.1 Flash-Lite |
|---|---|---|
| Chatbot Arena | 1320.0 | 1432.0 |
Deep dive
On shared benchmark coverage, Chatbot Arena has Gemini 2.5 Flash at 1320 and Gemini 3.1 Flash-Lite at 1432, with Gemini 3.1 Flash-Lite ahead by 112 points. The largest visible gap is 112 points on Chatbot Arena, which matters most when that benchmark mirrors your workload. Treat isolated benchmark wins as directional, because provider routing, prompt style, and tool access can move real application results.
The capability footprint is close: both models cover vision, multimodal input, function calling, tool use, and structured outputs. That makes context budget, benchmark fit, and provider maturity more important than a simple checklist. If your application depends on one integration detail, verify it against the provider route you plan to use, not just the base model listing.
For cost, Gemini 2.5 Flash lists $0.3/1M input and $2.5/1M output tokens, while Gemini 3.1 Flash-Lite lists $0.25/1M input and $1.5/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Gemini 3.1 Flash-Lite lower by about $0.33 per million blended tokens. Availability is 4 providers versus 2, so concentration risk also matters.
Choose Gemini 2.5 Flash when coding workflow support and broader provider choice are central to the workload. Choose Gemini 3.1 Flash-Lite when coding workflow support, larger context windows, and lower input-token cost are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which has a larger context window, Gemini 2.5 Flash or Gemini 3.1 Flash-Lite?
Gemini 3.1 Flash-Lite supports 1M tokens, while Gemini 2.5 Flash supports 1M tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, Gemini 2.5 Flash or Gemini 3.1 Flash-Lite?
Gemini 3.1 Flash-Lite is cheaper on tracked token pricing. Gemini 2.5 Flash costs $0.3/1M input and $2.5/1M output tokens. Gemini 3.1 Flash-Lite costs $0.25/1M input and $1.5/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Gemini 2.5 Flash or Gemini 3.1 Flash-Lite open source?
Gemini 2.5 Flash is listed under Proprietary. Gemini 3.1 Flash-Lite is listed under Proprietary. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, Gemini 2.5 Flash or Gemini 3.1 Flash-Lite?
Both Gemini 2.5 Flash and Gemini 3.1 Flash-Lite expose vision. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Which is better for multimodal input, Gemini 2.5 Flash or Gemini 3.1 Flash-Lite?
Both Gemini 2.5 Flash and Gemini 3.1 Flash-Lite expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Where can I run Gemini 2.5 Flash and Gemini 3.1 Flash-Lite?
Gemini 2.5 Flash is available on Google AI Studio, GCP Vertex AI, Replicate API, and OpenRouter. Gemini 3.1 Flash-Lite is available on Google AI Studio and OpenRouter. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-05-11. Data sourced from public model cards and provider documentation.