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CPA calculator
Cost per acquisition — what one conversion cost you in advertising. Pick the one you want and fill in the other two, including the direction that matters when planning: the budget a conversion target needs, or the conversions a budget should produce at a CPA you can afford.
- CPA
- = ad spend ÷ conversions
- ad spend
- = CPA × conversions
- conversions
- = ad spend ÷ CPA
Solve for
What the campaign cost over the period you are looking at.
Purchases, signups, installs — whatever you count as the action.
CPA
$33.33
Cost per acquisition
Target: under $36.00 first order · under $64.80 lifetime — profitable on the first order
Assumes a typical e-commerce shop — set your own economics ↓
$33.33=$5,000.00÷150
Your campaign, end to end
Every metric is two of these five numbers, divided. Follow a line to see which two. Open one and your campaign comes with you — fill a gap there and the rest fill in here.
What should these numbers be?
Not what a benchmark table says — those blend other businesses’ margins and customer values, which is why no two agree. Enter your own and every metric gets the range your economics can actually afford.
Revenue from a first conversion — order value for a shop, deal value × close rate for lead gen.
What is left of that revenue after cost of goods, shipping and fees.
Lifetime revenue ÷ the first order. Leave empty to judge on first orders alone.
- CPMunder $10.80 to profit on the first order · under $19.44 to break even over a lifetime
Yours is $10.00 — profitable on the first order.
- CTRabove 0.93% to profit on the first order · above 0.51% to break even over a lifetime
Yours is 1.00% — profitable on the first order.
- CVRabove 2.78% to profit on the first order · above 1.54% to break even over a lifetime
Yours is 3.00% — profitable on the first order.
- CPCunder $1.08 to profit on the first order · under $1.94 to break even over a lifetime
Yours is $1.00 — profitable on the first order.
- CPAunder $36.00 to profit on the first order · under $64.80 to break even over a lifetime
Yours is $33.33 — profitable on the first order.
- ROASabove 1.67× to profit on the first order · above 0.93× to break even over a lifetime
Yours is 1.80× — profitable on the first order.
How CPA is calculated
Divide what you spent by the conversions it produced. $5,000 for 150 conversions is a $33.33 cost per acquisition. A conversion here is whatever you have decided to count — a purchase, a signup, an install, a booked call — and the number only means something if that definition holds still between the campaigns you compare.
The planning direction is the same relationship read backwards. If you can afford $33.33 per acquisition and need 150 of them, the budget is $5,000. Set the calculator to solve for ad spend and put your target CPA in.
CPA, CPL and CAC are not the same number
CPA counts the action you told the ad platform to optimise for, and counts only advertising spend. CPL narrows that action to a lead. CAC is the whole cost of winning a customer — advertising plus the sales and marketing effort that turned a lead into one — divided by customers, not conversions.
Mixing them is how a channel looks profitable in the ad account and unprofitable in the P&L. If you sell through a sales team, the gap between your CPA and your CAC is that team, and the ad platform cannot see it.
FAQs
Frequently Asked Questions
How do you calculate CPA?
Divide the total cost of the campaign by the number of conversions it generated. $5,000 spent for 150 conversions is 5,000 ÷ 150 = a $33.33 cost per acquisition.
What is the CPA formula?
CPA = ad spend ÷ conversions. Rearranged, conversions = ad spend ÷ CPA, and ad spend = CPA × conversions. Choose which of the three you want at the top of the calculator.
How do I work out my target CPA?
Start from what a customer is worth to you rather than from an industry average. Take the gross profit on an average order — revenue minus cost of goods, shipping and payment fees — and decide what share of it you are willing to spend to win the sale. That share is your ceiling. If a customer nets you $80 and you are prepared to spend half of it on acquisition, your target CPA is $40, and any campaign above that is buying revenue at a loss unless it earns it back on repeat purchases.
Does CPA mean cost per acquisition or cost per action?
Both, and in advertising they are used interchangeably — the "acquisition" is just whichever action you are counting. It is worth noting the term also means Certified Public Accountant in an entirely different field, which is why searching for a CPA calculator turns up accounting tools; this one is the advertising metric.
What is a good CPA?
One below the gross profit on what you sold, with enough room left over to cover everything advertising does not. Published cross-industry averages are close to useless here, because a good CPA for a $2,000 B2B contract and a good CPA for a $25 consumable differ by two orders of magnitude and neither is described by the mean. Work it out from your own margin instead, then compare campaigns against that number rather than against each other. The targets section under the funnel below computes it: enter your margin and conversion value and the ceiling appears, on the first order and over a customer lifetime.
Why is my CPA higher than the platform reports?
Attribution windows, usually. Platforms count conversions they can claim within their own window and often on view-through as well as click-through, so a platform-reported conversion count runs ahead of what your own analytics or order system sees. Calculate CPA from the conversion count you actually trust, and use the same source every time you compare.
How do CPA, CPC and conversion rate fit together?
CPA is CPC divided by conversion rate. A $1.00 click that converts 3% of the time gives a $33.33 cost per acquisition. That means a cheaper click and a better landing page move CPA by exactly the same mechanism, and it tells you where to look when CPA rises: if CPC held steady, the problem is after the click.
Is it free, and do you keep what I type?
Free, with nothing to sign up for. The arithmetic runs in your browser — typing a number makes no server request, and there is no store of what visitors enter, so your figures cannot end up in anyone’s benchmark. Your numbers do go into the page URL so you can bookmark or share the result, which means they travel in any link you send.
