Cost Per Tap (CPT) is what an advertiser pays each time someone taps an Apple Ads Advanced ad, with the max CPT bid setting a ceiling rather than the price actually paid.
CPT is how Apple Ads Advanced (formerly Apple Search Ads) bills across its App Store placements: you pay when someone taps your ad, not when it's shown. Apple Ads Basic is the exception and charges per install. Outside Maximize Conversions campaigns you set a max CPT bid, the most you'll pay for a tap. Apple treats it as a ceiling; the actual price comes from a dynamic auction that weighs ad relevance, your bid, other advertisers' bids, any reserve price and the overall user experience, so average CPT can land below the max. Maximize Conversions search results campaigns bid automatically toward a target CPA but still charge per tap.
CPT only means something once it's joined to what follows the tap. Cost per install is roughly CPT divided by the tap-to-install conversion rate, so a $2 tap that converts at 50% costs $4 per install, and a stronger product page lowers acquisition cost without touching the bid. That makes CPT an ASO lever as much as a bidding one: the icon, screenshots and ratings that lift organic conversion also make every paid tap cheaper to turn into a user. Apple's own bid guidance works back from what an install is worth; our Apple Search Ads calculator runs that break-even math.
Example
A language-learning app sets a $3.00 max CPT on "learn spanish" and pays an average of $2.10 over the month. Half of those taps become installs, so each install costs about $4.20, which the team checks against day-30 revenue per user before raising the bid.