What is CPA?
Cost per acquisition is the media cost of getting one conversion: a sale, a lead, a signup. Spend divided by conversions. It is the price you pay for a result, and one of the most used steering metrics in performance marketing.
What a good CPA depends on
- Unit economics: a sustainable CPA is set by margin and customer lifetime value, not by last year's average or a competitor's rumour.
- The conversion definition: a lead CPA and a sale CPA are different animals; mixing them creates fake precision.
- Funnel role: prospecting acquires new customers at a higher CPA than retargeting harvests old intent. Different jobs, different prices.
The trap
Squeezing CPA is the fastest way to shrink an account. The cheapest conversions come from people who were already convinced: brand searchers, past visitors, existing customers. Push CPA down hard enough and the algorithm serves only them, the account looks efficient, and new customer growth quietly dies.
How to use it well
Set CPA targets from the economics, split them by funnel role, and always read CPA next to volume and new customer share. A slightly higher CPA that doubles new customers is a bargain; a beautiful CPA on a shrinking base is a slow leak.
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