Paid Media
CPA Calculator
Cost per acquisition is the number I check before anything else in an account. It is what one completed outcome actually costs you. Enter spend and conversions to get your CPA, then set a target to see how much volume the same budget would buy at a better price.
Result
FormulaCPA = total spend ÷ conversions
Worked example
A campaign spends $12,000 and produces 240 conversions, so CPA is $50. Getting to a $40 target on the same budget would deliver 300 conversions, 60 more outcomes with no extra money. Read the other direction too: holding volume at 240 conversions at $40 each would only cost $9,600, freeing $2,400 to test elsewhere.
What to watch for
CPA is only meaningful next to what a customer is worth. A $50 CPA is excellent for a $600 order and disastrous for a $40 one, so I never approve a CPA target that was not derived from margin.
Watch conversion definitions before you compare periods. Adding a soft action like a newsletter signup to your conversion column will drop reported CPA overnight while the business gets nothing new, and that fake improvement gets repeated in a board deck for months.
Across agency accounts, the fastest CPA wins usually come from cutting waste rather than raising bids: search terms that never convert, geographies that never close, and placements that inflate volume with junk.
Frequently asked questions
What is a good CPA?
There is no universal number. Work backwards instead: take your gross profit per customer, decide what share of it you are willing to pay to acquire one, and that is your ceiling. Anything under it is good, anything over it is a subsidy.
What is the difference between CPA and CAC?
CPA is usually channel level and counts a platform-reported conversion. CAC is company level and counts real new customers against all acquisition costs including salaries and tools. CPA is a steering wheel, CAC is the odometer.
Why did my CPA rise when I increased budget?
Because you moved past the cheapest available demand. Scaling almost always means buying incremental, less qualified inventory, so plan for a higher CPA at higher spend and set the target at the volume level you actually want, not at your best small-budget week.
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This calculator runs entirely in your browser. Nothing you enter is sent to a server, logged, or stored. Figures are for planning and do not constitute financial advice. See disclosures.