Gemini 3.1 Pro Preview API Pricing: Cost Calculator & Real Examples (2026)
Gemini 3.1 Pro Preview charges $2.00 per 1 million input tokens and $12.00 per 1 million output tokens. But per-token prices don't answer the real question: what will your workload cost per month? Below we compute it for three realistic scenarios — or run your own numbers with Gemini 3.1 Pro Preview preselected.
| Meter | Price per 1M tokens |
|---|---|
| Input | $2.00 |
| Cached input | $0.20 |
| Output | $12.00 |
Note: Prompts ≤200k tokens; larger prompts cost $4/$18 per 1M.
What does Gemini 3.1 Pro Preview cost in practice?
| Monthly scenario | Token bill |
|---|---|
| Support chatbot (150k requests, 400 in / 300 out tokens) | $660.00 |
| Document workflow (22k runs, 3,000 in / 400 out tokens) | $237.60 |
| High-volume classifier (1M requests, 300 in / 10 out tokens) | $720.00 |
In the chatbot scenario, output is ~82% of the Gemini 3.1 Pro Preview bill — capping response length (max tokens) is the most direct optimization. Document workflows are input-heavy, so the input rate dominates there.
Prompt caching savings
Gemini 3.1 Pro Preview offers cached input at $0.20/1M (vs $2.00 standard). At a 60% cache-hit rate, the example chatbot drops from $660.00 to $595.20/month — saving $64.80. If your system prompt and context are stable, this discount is free money.
Is Gemini 3.1 Pro Preview cheap or expensive?
On the same chatbot workload, Gemini 3.1 Pro Preview is cheaper than 5 of the 13 models we track (position 9 of 14, cheapest to priciest). The nearest cheaper alternative is Claude Sonnet 5 ($570.00/month on the same scenario). One step up: GPT-5.6 Terra ($825.00/month). The right decision isn't absolute price but the cheapest model that meets your quality bar — test before overpaying.
FAQ
How much does Gemini 3.1 Pro Preview cost per 1M tokens?
$2.00 per 1M input tokens and $12.00 per 1M output tokens (verified 2026-07-09).
What does a chatbot cost on Gemini 3.1 Pro Preview?
A 500-active-user chatbot (10 questions/day, 400 input + 300 output tokens per request) costs ~$660.00/month in tokens on Gemini 3.1 Pro Preview. Adjust the assumptions in the calculator.
Prices verified on 2026-07-09 against the provider's official pricing page. Estimates are for planning purposes only — always confirm current pricing with the provider.