About Gemini 3.1 Pro Preview
Gemini 3.1 Pro Preview is the reasoning flagship of Google's Gemini 3 line as offered through the Gemini API, pitched by Google around advanced intelligence, complex problem-solving and agentic and vibe-coding capability. The Preview label is doing real work in the name: Google ships it for production use but reserves the right to revise behaviour before a stable release, which argues for pinning and re-testing in anything customer-facing.
It shares the family's fully multimodal input and million-token-class context window, and sits above the Flash tiers as the model you escalate to when they run out of depth.
Pro pricing is two-dimensional: beyond the standard rates, prompts past Google's long-context threshold are billed at higher input and output rates for the request — the callout above carries the figures — so workloads that routinely stuff the context window pay a structural premium, not just a linear one. Its cache storage fee is also the steepest in Google's lineup, which pushes caching economics toward high-traffic services only. For prompt sizes under the threshold it compares naturally with other frontier reasoning tiers; the rivals table above puts numbers on that for a mixed workload.
Frequently asked questions
How much does the Gemini 3.1 Pro Preview API cost?
Gemini 3.1 Pro Preview costs $2 per million input tokens and $12 per million output tokens, with cached input at $0.2 per million (90% off). Note: Prompts over 200K tokens: $4 in / $18 out. Cache storage $4.50/MTok/hour.
How much does a typical chat message cost with Gemini 3.1 Pro Preview?
A short chat message (about 500 input and 250 output tokens) costs roughly $0.0040 with Gemini 3.1 Pro Preview. At 1,000 such requests a day, that is about $120.00 per month.
Is Gemini 3.1 Pro Preview cheap compared to similar models?
Gemini 3.1 Pro Preview has the #19 cheapest input rate of the 29 models we track. On a mixed workload (10K input / 2K output), it costs $0.044 per request, versus $0.040 for Claude Sonnet 5 and $0.045 for GPT-4o.
What does Gemini 3.1 Pro Preview cost per 1,000 tokens?
Per 1,000 tokens, Gemini 3.1 Pro Preview costs $0.0020 for input and $0.0120 for output, or $0.00020 for cached input. Providers quote rates per million tokens ($2/M in, $12/M out here), so divide by a thousand for the per-1K figure older pricing pages used.
How large a prompt can Gemini 3.1 Pro Preview take?
Gemini 3.1 Pro Preview accepts up to 1024K tokens of input context and can generate up to 64K tokens of output per request. At its input rate, filling the entire 1024K-token window costs about $2.10 per request before any output.
Related
Compare all models at once ·Count tokens in your prompt
All Google model costs: Gemini 3.8 Flash · Gemini 3.7 Flash · Gemini 3.6 Flash · Gemini 2.5 Pro · Gemini 2.5 Flash · Gemini 2.5 Flash-Lite
Last updated 2026-09-03. Prices verified against Google's official pricing page; see the methodology.