Monthly cost comes from four numbers multiplied through:
(input tokens / request) × (requests / day) × 30 × ($ / 1M input tokens) ÷ 1,000,000
+ (output tokens / request) × (requests / day) × 30 × ($ / 1M output tokens) ÷ 1,000,000
That is the whole shape. Count the tokens, multiply by your volume and
the per-token price. This kind of first-principles estimation - get the
order of magnitude before you reach for a spreadsheet - is the method
Simon Eskildsen collects at
napkin-math
(notes, MIT-licensed reference numbers revalidated on real cloud hardware). It is the same instinct that let
turbopuffer
prove vector search could be built far cheaper than incumbents charged - and turn it into one of Canada's fastest-growing AI companies.
We apply a 0.8 shared-seat factor for teams (not every seat fires at full
rate at once), matching the assumption our
budget tool
uses so the two pages agree.
Reference numbers and the napkin-math method are Eskildsen's work - we point to it, we did not invent it.