CPA calculator
Cost per acquisition and conversion rate from your spend, and the maximum CPA your average order and margin can take.
Spend, conversions and clicks
Max CPA from your margin
Everything runs in your browser: no number is sent anywhere.
What is CPA?
CPA is the cost per acquisition: what you pay, on average, for each conversion, whether a sale, a lead or a sign-up. It is the price metric for performance campaigns and the closest to the business, because it combines the price of the click with the page’s conversion rate.
How to calculate CPA: the formula
CPA = spend ÷ conversions. With clicks, you can also see the conversion rate: conversions ÷ clicks × 100. CPA can also be written as CPC ÷ conversion rate, which shows the two levers for lowering it: pay less per click or convert more of the clicks you already have.
Example: $5,000 with 78 conversions is a $64.10 CPA. With 5,200 clicks, the conversion rate is 1.5%.
What is the maximum CPA a campaign can take?
The break-even CPA is the average order multiplied by the contribution margin: what is left of each sale after product cost, taxes, shipping and fees. Above it, each sale loses money; below it, each sale makes money. For sales campaigns, the same reasoning on top of revenue is the break-even ROAS.
Example: a $250 average order and a 36% margin give a $90 maximum CPA. With an actual CPA of $64.10, each sale leaves $25.90.
Platform CPA and GA4 CPA
The ad platform and GA4 count conversions with different rules: attribution window, view-through and attribution model. The two CPAs rarely match, and that is not a bug. What has to match is the campaign: for the conversion to show up in GA4 under the right ad, the link needs UTMs. The guide Meta sales don’t match GA4 shows how to compare them.
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Frequently asked questions
Are CPA and CPL the same thing?
CPL is cost per lead, a special case of CPA where the conversion is a lead. The math is the same: spend divided by the number of leads.
Should I use platform or GA4 conversions in the calculation?
Use the same source whenever you compare periods or campaigns. The platform is for optimizing the auction; GA4 is for comparing channels against each other with the same ruler.
Does the calculator send my numbers anywhere?
No. The math runs in your browser and nothing is sent to any server.