The instrument
Five CPM scenarios, worked end to end
By Oliver Wakefield-Smith · updated July 2026
The short answer
Formulas stick when they carry real numbers. Five named buying situations, each computed by the same arithmetic as the calculator: a $1,000 Meta test, a podcast mid-roll purchase, YouTube's buyer-to-creator flip, the Q4 repricing and the reach-frequency trade. Every rate used is sourced and dated.
74,184 impressions
The $1,000 test budget
What $1,000 buys on Meta at the sourced global median, and whether that is enough to learn anything.
$360
The podcast mid-roll buy
A 30-second host-read on a 20,000-download show at AdvertiseCast's $18 CPM, invoice math included.
$10.00 in, $4.68 out
The YouTube flip side
The same video: what the advertiser pays vs what the creator receives after YouTube's published 45% cut.
Jun vs Nov
The Q4 holiday surge
Same campaign, two dates: how auction pressure reprices identical impressions, with arithmetic at stated multiples.
R × F = I
Reach vs frequency
A fixed budget split between reaching more people and reaching the same people more often.
Want the blank version? The calculator runs the same three solves with your numbers, and the formula page shows the rearrangements the scenarios lean on.