Google's newest Flash model is sold at half price — the half is against its own 2027 rate, and the real generational cut is 14%

Google's public price list for the Gemini API contains thirty model entries. Exactly two of them carry a dated expiry: Gemini 3.7 Flash, announced on 13 August 2026, and Gemini 3.6 Flash before it. Both are listed at USD 0.75 per million input tokens and USD 3.75 per million output tokens "through December 31, 2026", and at USD 1.50 and USD 7.50 "starting January 1, 2027". The expiry applies to every tier the page shows for those models — standard, batch, flex and context caching alike, the last of which goes from USD 0.075 to USD 0.15, with cache storage doubling from USD 0.50 to USD 1.00 per million tokens per hour. We ran the arithmetic the coverage skips. A job consuming one million input tokens and producing one million output tokens costs USD 4.50 on Gemini 3.7 Flash today and USD 9.00 from 1 January — the bill doubles overnight, with no change to the model. The same job on Gemini 3.5 Flash, which Google prices at USD 1.50 and USD 9.00 with no end date, costs USD 10.50. That third number is the one that matters, because it is the comparison that survives the promotion. Against the Flash model it supersedes, Gemini 3.7 Flash is permanently 14.3% cheaper, not 57% cheaper. The input price does not move at all: USD 1.50 before and after. The entire durable saving sits in output tokens, down from USD 9.00 to USD 7.50, or 16.7%. There is a second consequence that follows from the same table. Gemini 3.6 Flash carries an identical rate in both periods, promotional and standard. The two models therefore cost exactly the same to run today and will still cost exactly the same in January, which makes the upgrade from 3.6 to 3.7 free in cash terms — the benchmark gaps between them are large (DeepSWE v1.1 rises from 49.0% to 65.3%, FrontierCode 1.1 from 34.4% to 43.6%) and cost nothing. A third follows for anyone planning around the batch tier: from 1 January batch runs at USD 0.75 and USD 3.75, which is precisely what standard costs in August. The batch discount in 2027 buys back today's ordinary price. What none of this establishes is that the rise will happen. A promotional rate can be extended, and Google has extended introductory pricing before; the page states an end date, not a commitment to enforce it. But a price with a date on it is not the same object as a price without one, and readers comparing Flash-class models on cost this month are comparing two figures that expire against one that does not.