Flat AI plans hide the one number you need: how much work the meter lets through before it stops you.
API cost per task is measurable. Across 132 graded agent runs on a small repo (TinyDB, about 2k lines), a hard coding task cost about $0.12 on GPT-6.1 Sol at medium effort. At that rate, $200 of API buys roughly 1,660 hard tasks a month, around 79 per working day.
High effort roughly doubled the cost with no gain in pass rate. Across task mix and effort settings, break-even swings by more than 9x, which matters more than $200 vs $500.
That is why the reported Pro allowance cut (20x Plus down to 10x, press-reported, not confirmed by OpenAI) is a capacity change, not a price change. Same price, a lower ceiling with no published number. Before Oct 29, log a week of your real tasks through the API, with input, output and cache tokens, and see how much of your allowance you actually burn.
Full numbers and the limits of the test: The $200 OpenAI Pro Plan Has a Math Problem
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