This free cpa calculator shows the cost per acquisition of a campaign from its total spend and the number of conversions it produced — and in reverse it estimates how many sales or leads a budget should deliver at a target CPA, or what a conversion goal will cost.
CPA is what each sale, sign-up or lead actually costs you in ad spend. Enter any two values and the third is worked out for you.
What the campaign spent in total.
Sales, sign-ups or leads the spend produced.
The average amount paid for each conversion.
Used for the money figures only — the maths is the same.
Enter any two values and the third is worked out for you. The formula is CPA = Total Cost ÷ Conversions. Everything runs in your browser; nothing is uploaded or stored.
How this cost per acquisition calculator works
A conversion can be a purchase, a completed sign-up or a qualified lead — whatever action the campaign exists to produce. The tool has three inputs: total cost, conversions, and the CPA itself, plus a currency selector that only changes how money figures are displayed. Fill in any two values and the third is recalculated instantly, always updating the field you have edited least recently. No figures leave your browser.
The CPA formula
CPA = Total Cost ÷ Conversions. A campaign that spends $500 and produces 25 conversions has a CPA of $20.00. In reverse, Conversions = Total Cost ÷ CPA shows what a budget should deliver, and Total Cost = Conversions × CPA shows what a conversion target will cost.
How CPA, CPC and conversion rate connect
Your cost per action is driven by two levers: CPA = CPC ÷ Conversion Rate. At a $2.00 cost per click and a 10% conversion rate, each conversion costs $20. Halve the click price or double the conversion rate and the same conversion costs $10 — which is why landing page improvements often beat bid changes.
How to bring your cost per action down
Improve the landing page so more of the clicks you already pay for turn into conversions, and cut the campaigns and keywords that spend without converting. Just as important, make sure conversion tracking counts the actions that actually matter to the business — a CPA measured against the wrong action points every decision the wrong way. Compare paid results against organic with the SEO ROI Calculator.
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Frequently asked questions
Directly: at the same CPC, doubling your conversion rate halves your CPA, because twice as many clicks turn into conversions for the same spend.
Divide the total campaign cost by the number of conversions. $500 ÷ 25 conversions = a $20.00 CPA.
No. The calculation runs entirely in your browser and the figures you enter are never uploaded or stored.
A good CPA is one comfortably below the profit a conversion brings you. The same $20 CPA can be excellent for a high-margin product and unsustainable for a low-margin one.
CPA (cost per acquisition, also called cost per action) is the average ad spend needed to produce one conversion — a sale, a sign-up or a lead.
An automated bidding approach in Google Ads where you set the average cost per conversion you are willing to pay, and bids are adjusted to aim for it. Your actual CPA will still vary from campaign to campaign.
CPA measures the ad cost of one conversion in a campaign. CAC (customer acquisition cost) usually counts all sales and marketing costs across the business divided by new customers gained.