CPA
Cost per result
What you actually pay for one result — an order, a booking or a conversation — depending on the event you chose to measure.
Formula
CPA = ad spend ÷ number of results
How to read it
- Before reading the figure, know which event it counts: add-to-cart, conversation started and completed order are three different numbers, and the gap between them is wide.
- The correct ceiling comes from your margin: the most you can pay per order is your contribution per order, and anything above it is selling at a loss.
- A rising cost is not always an advertising problem — a slow checkout or a late reply to messages shows up here too.
The common mistake
Taking comfort in a low cost for a weak event: a hundred cheap add-to-carts look like success until you find four of them became orders. Read the cost at the event that reaches the bank.