💡 This is a cross-post from my AI Cost Calc blog . The original has the same content with linked tools — feedback welcome on either platform. "Cheapest AI API" is a misleading question. The model that costs the least per token might be useless for your task — and the one that looks expensive might be 10× cheaper for what you actually use it for . So before we hand you the list, two caveats: Cost is meaningless without capability matching. A $0.20/1M model that gets 60% of your queries wrong is more expensive than a $5/1M model that nails them on the first try. Headline rates lie in 2026. Caching can cut bills by 90%. Batch API drops them 50%. The "cheapest" model on the price page might be the most expensive in production. With those out of the way: here's the honest ranking by single-call cost (1,000 input + 500 output tokens) across 10 frontier and small models.…