Efficiency
What is CPA?
Also: Cost per acquisition · Cost per action · CPP (cost per purchase)
CPA (cost per acquisition) is ad spend divided by the number of conversions (purchases, leads, or the chosen action).
CPA = ad spend / conversions
CPA is the inverse view of ROAS: instead of revenue per dollar, it is dollars per result. It is the natural north-star for lead-gen and for Search campaigns where value varies, and it is directly comparable across campaigns aiming at the same action. What counts as the 'action' must be fixed, or the number is meaningless.
Last reviewed 2026-09-19
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