Gemini 3.8 Flash vs Gemini 3.1 Flash-Lite: which API costs less?
Averaged across three realistic workloads, Gemini 3.1 Flash-Lite is about 63% cheaper than Gemini 3.8 Flash. Below: raw rates and side-by-side monthly costs, computed from prices verified 2026-10-17 (we track what you are billed today, promos included).
Rates per 1M tokens
| Model | Input | Output | Cached input |
|---|---|---|---|
| Gemini 3.8 FlashGoogle | $0.750 | $3.75 | $0.075 |
| Gemini 3.1 Flash-LiteGoogle | $0.250 | $1.50 | $0.025 |
Gemini 3.8 Flash: Launch price until Dec 31, 2026; $1.50/$7.50 announced from Jan 1, 2027.
Monthly cost, side by side
| Workload | Gemini 3.8 Flash | Gemini 3.1 Flash-Lite | Difference |
|---|---|---|---|
Customer-support chatbot 2M input + 0.5M output tokens/month, 60% of input served from prompt cache | $2.56 | $0.980 | Gemini 3.1 Flash-Lite −62% |
RAG / document Q&A 20M input + 1M output tokens/month, 70% cached (shared context) | $9.30 | $3.35 | Gemini 3.1 Flash-Lite −64% |
Agentic coding assistant 50M input + 5M output tokens/month, 80% cached (long sessions) | $29.25 | $11.00 | Gemini 3.1 Flash-Lite −62% |
Your traffic looks different? Run your own numbers in the calculator.
FAQ
Which is cheaper: Gemini 3.8 Flash or Gemini 3.1 Flash-Lite?
Across three realistic workloads (chatbot, RAG, agent), Gemini 3.1 Flash-Lite works out about 63% cheaper than Gemini 3.8 Flash on average. Raw rates: Gemini 3.8 Flash $0.750/$3.75 per 1M tokens vs Gemini 3.1 Flash-Lite $0.250/$1.50. Verified 2026-10-17.
Does prompt caching change the comparison?
Yes — cached input costs $0.075 on Gemini 3.8 Flash and $0.025 on Gemini 3.1 Flash-Lite. Our scenario numbers already include realistic cache hit rates.
Is cheaper always better?
No. Price is one axis — model capability, context window and latency differ. This page answers only the cost question; benchmark quality on your own tasks before switching.