AI Plan Economics 2026: when a flat monthly AI plan stops being cheaper than the API

For each consumer AI plan whose price was read from the provider page, how many tasks of three declared sizes the same money buys at that provider's own API list prices, at a small, a middle and a flagship model. Prices are provider-stated and dated; task sizes are declared assumptions; the break-even is arithmetic, not advice. Includes the measured tokens-per-word join from the Tokenizer Inflation Ledger. Method, limits and the interactive calculator: https://nesyona.com/research/ai-plan-economics-2026/ . Every provider price is archived with a SHA-256 in the AI Price Watch evidence archive. Released under CC BY 4.0.