# Gemini 3.1 Pro Preview pricing, and the date nobody wrote down > Gemini 3.1 Pro Preview pricing is $2.00 per million input and $12.00 output. Preview rates move, so a forecast pinned to one ages fastest. URL: https://getculpa.com/gemini-3-1-pro-preview-pricing Last reviewed: 2026-08-01 Rates effective: 2026-07-02 ## Answer Gemini 3.1 Pro Preview pricing is $2.00 per million input tokens and $12.00 per million output tokens. Preview rates carry no commitment, so a forecast built on this one ages faster than any other number in your model. Culpa, a local-first LLM cost, margin, and forecast ledger, prices every call from a dated price book, so a rate change lands as a diff rather than as a surprise. ## Why this happens Every other rate in this book is a published price with no stated end. A preview rate is a different kind of number: it exists to get the model tried, and it changes when the model reaches general availability. Teams build a forecast on it anyway, because it looks exactly like a normal rate on the page. There's precedent for what happens next. Claude Sonnet 5's introductory pricing rose 50% on a published date, and the workloads pinned to the old rate had that increase land with no action on their side. ## What this usually looks like - A preview model is carrying production traffic and the forecast treats its rate as fixed. - Nobody has written down what happens to the budget if the rate rises at general availability. - The migration path off the preview model has never been costed or tested. - Your cost model stores one rate per model with no effective date beside it. ## Common mistakes - Forecasting a preview rate as though it were permanent. Why it hurts: The rate exists to encourage adoption, so the direction of travel is usually upward. Do instead: Forecast a band, and put the upper end at what the stable tier in the same family charges. - Putting production traffic on a preview model with no exit. Why it hurts: A rate change or a deprecation both land as an emergency rather than as a scheduled task. Do instead: Keep a tested fallback and know what the same workload costs on it. - Storing one rate per model with no effective date. Why it hurts: A dated change can't be modelled at all if the data structure has nowhere to put the date. Do instead: Store rates with effective dates and price each call at the rate in force when it was made. ## Self-check - List every preview or experimental model carrying production traffic. - Price this month's volume at the current preview rate and at the stable tier's rate. - Write down the gap. That's the exposure nobody has approved. - Confirm a tested fallback exists and that somebody has priced the same workload on it. - Check whether your cost model can even represent a rate that changes on a date. ## The band around a preview forecast (illustrative) A workload of 200 million input and 40 million output tokens a month on Gemini 3.1 Pro Preview at real rates, with two plausible landing points at general availability. Volumes are modelled and the landing points are scenarios, not announcements. At the preview rate: (200 x $2.00) + (40 x $12.00) = $400 + $480 = $880 If it settles at Gemini 2.5 Pro's rates of $1.25 and $10.00: $250 + $400 = $650, which is 26% cheaper If it rises 50%, matching the precedent set by Claude Sonnet 5: $600 + $720 = $1,320 The forecast band is $650 to $1,320 around a current figure of $880 Nothing on the rate card narrows that band, because a preview rate carries no commitment The honest forecast is a band twice as wide at the top as at the bottom, not a number. Publishing $880 as a plan figure states a precision the underlying rate has never offered. ## Cost figures Every figure carries its confidence and its source. No figure on this site is provider-reported. - $2.00 / $12.00 per million — Gemini 3.1 Pro Preview input and output rates, with no commitment to stay there [calculated] Source: Culpa price book row for gemini/gemini-3.1-pro-preview, $0.002 and $0.012 per 1k, effective 2026-07-02, verified against Gemini API pricing. Shown here per million. - $650 to $1,320 — modelled monthly cost band for the same workload if the preview rate settles lower or rises [estimated] Source: Both endpoints from the teardown arithmetic. The lower uses real Gemini 2.5 Pro rates and the upper applies the 50% rise Claude Sonnet 5's introductory pricing took. Volumes are modelled and neither landing point is announced. ## FAQ Q: How much does Gemini 3.1 Pro Preview cost? A: $2.00 per million input tokens and $12.00 per million output, with context caching at $0.20 per million. Rates verified against Google's pricing page, and preview rates carry no commitment to stay there. Q: Should I run production traffic on a preview model? A: Only with a tested fallback and a forecast expressed as a band rather than a number. The rate exists to encourage adoption, so plan for it moving, and know in advance what the same workload costs on the stable tier. Q: Does a preview rate usually go up? A: Neither direction is settled, and both have precedent. Claude Sonnet 5's introductory pricing rose 50% on a published date, while a preview model settling near an existing stable tier can land cheaper. Forecast the band, not the point. ## Sources - Gemini API pricing: https://ai.google.dev/gemini-api/docs/pricing Run the free Cost Leak Scan: https://app.getculpa.com/scan?source=pseo&slug=gemini-3-1-pro-preview-pricing&cluster=model_pricing Machine-readable index of every guide: https://getculpa.com/api/pages Human-readable index of every guide: https://getculpa.com/guides Site overview: https://app.getculpa.com/llms.txt Privacy: Culpa runs on your infrastructure. Your prompts and responses never leave it. Culpa counts calls to run your plan, and it fails open, so if it ever breaks your app keeps running.