Free tool CPA calculator: cost per acquisition formula and target CPA
CPA is the ad spend behind one conversion. Choose what counts as an acquisition (a lead, a sign-up or a purchase), enter spend and conversions, and add order value and margin to see the most you can pay per conversion before you lose money.
- Lead, sign-up or purchase
- Break-even CPA
- Runs locally
Work out CPA and the CPA you can afford
Spend and conversions give CPA. Order value and gross margin are optional; with them you get a break-even CPA. For leads and sign-ups, add the share that become paying customers.
Use the same conversion the ad platform optimises for, or the one you report on.
Spend on the campaign or channel for the period.
Leads, sign-ups or purchases in the same period.
For purchases, average order value. For leads and sign-ups, what a new customer pays (first order or first-year revenue).
Share of that revenue left after product, delivery and payment costs.
Share of sign-ups that become paying customers.
Share of leads that close.
CPA (cost per acquisition)
$30.00
Ad spend ÷ conversions.
Share these inputs: the values go after the # in the link, so they never reach a server.
https://tapcub.com/tools/cost-per-acquisition-calculator
Version v1.0Updated Update history
What the four numbers mean
CPA tells you what a result cost. Break-even CPA tells you what a result is worth. The gap between them is the decision.
CPA
Ad spend per conversion. $6,000 for 200 purchases is a $30 CPA. Only comparable between channels that count the same conversion.
Break-even CPA
The most you can pay for one conversion and still cover it from gross profit. A $90 order at 40% margin leaves $36, so $36 is the line.
Ad cost per paying customer
For leads and sign-ups, CPA ÷ the share that pay. A $20 lead that closes 10% of the time costs $200 per customer in ad spend.
CPA vs CAC
CPA is ad spend per conversion, usually per channel. CAC is all sales and marketing cost (salaries, tools, agencies) per new paying customer. CAC is almost always higher; work it out with the CAC calculator.
Break-even CPA here uses the first order or first-year revenue. If customers come back, the value of a customer is higher; the customer lifetime value calculator estimates it for subscriptions.
Three steps
Define the conversion first, then the numbers follow.
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1
Pick the acquisition
Purchase, sign-up or lead. Use one definition per comparison; a lead CPA and a purchase CPA are different metrics.
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2
Enter spend and conversions
From the same campaign and date range. Prefer conversions you measure on your own site over what the ad platform credits itself.
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3
Add value and margin
Order value (or what a new customer pays) and gross margin give the break-even CPA. For leads and sign-ups, add the close rate.
CPA = ad spend ÷ conversions
Cost per acquisition spreads ad spend over the conversions it produced. The break-even CPA is the gross profit one conversion brings in.
- Break-even CPA (purchase) = average order value × gross margin
- Break-even CPA (lead or sign-up) = revenue per customer × gross margin × conversion-to-customer rate
- Target CPA = break-even CPA − the profit you want to keep per conversion. Break-even CPA and break-even ROAS (1 ÷ margin, see the ROAS calculator) describe the same line
CPA
CPA = spend ÷ conversions
$6,000 ÷ 200 purchases → $30.00
Break-even CPA
AOV × gross margin
$90 × 40% → $36.00 (room $6.00)
Per paying customer
CPA ÷ lead-to-customer rate
$20 per lead ÷ 10% → $200.00
One budget, three definitions of acquisition
A software company spends $6,000 on one campaign and counts results three ways. The CPA changes by 20 times; the cost per paying customer does not change at all.
| Acquisition counted | Conversions | CPA | Share that pay | Ad cost per paying customer |
|---|---|---|---|---|
| Lead (demo request) | 600 | $10.00 | 5% | $200.00 |
| Free trial sign-up | 150 | $40.00 | 20% | $200.00 |
| Paid subscription | 30 | $200.00 | 100% | $200.00 |
A $10 lead CPA and a $200 purchase CPA describe the same campaign. Compare channels on the same row, and carry lead or sign-up CPAs through to the paying customer before judging them. Sample figures.
Where CPA goes wrong
Most bad CPA decisions come from comparing numbers that measure different things.
Different conversions per channel
A lead on one channel and a purchase on another produce CPAs that cannot be compared. Use one conversion for every row.
Platform-credited conversions
Each ad platform counts the conversions it touched, often including views without a click. Added up, they exceed your real orders, and CPA looks too low.
Revenue instead of margin
A break-even CPA of the full order value ignores product and delivery cost. Use gross margin, or you pay more than a sale earns.
Calling CPA "CAC"
CPA leaves out salaries, tools and agency fees. Reporting it as CAC understates what customers really cost.
Conversions counted on your site, by campaign
A CPA is only as good as its conversion count. TapCub records conversions on your own site, app or mini program, keeps the campaign that brought the visitor, and puts imported spend next to it.
Campaign and channel reports
Sessions, conversions and conversion rate per campaign, source and medium.
Learn moreChannel ROI
Import spend per channel and see return next to the traffic it bought.
Learn moreFirst and last touch
The campaign that introduced a customer and the one that closed, on the same person.
Learn moreCPA questions
Still have a question?
Chat with the team behind TapCub — we usually reply within a few hours on business days.
How do I calculate cost per acquisition (CPA)?
The cost per acquisition formula is CPA = ad spend ÷ conversions. $6,000 that produced 200 purchases is a CPA of $30. Decide first what counts as a conversion: a purchase, a sign-up or a lead give very different CPAs.
How do I calculate a target CPA?
Start from the break-even CPA: average order value × gross margin. A $90 order at 40% margin breaks even at $36. Subtract the profit you want to keep per order to get the target. For leads, also multiply by the lead-to-customer rate.
Is CPA the same as cost per lead (CPL)?
Cost per lead is a CPA where the acquisition is a lead. Many teams say CPA only for purchases or paid sign-ups and CPL for leads. Whichever you use, say which conversion it counts, and convert a CPL into cost per paying customer by dividing by the close rate.
What is the difference between CPA and CAC?
CPA is ad spend per conversion, usually for one channel, and the conversion can be a lead or sign-up. CAC is all sales and marketing cost divided by new paying customers. The CAC calculator does the second.
What is a good CPA?
One that is below what a conversion is worth to you. That depends on your price, margin and how often customers come back, so another company's CPA tells you little. Compare your CPA with your break-even CPA.
Should I use the CPA reported by Google Ads or Meta?
Use it for optimising inside that platform. For comparing channels, count conversions in one place (your own analytics), because each platform credits itself, sometimes for the same order.
How is CPA related to CPC?
CPA = CPC ÷ conversion rate. A $1.50 click with a 5% conversion rate costs $30 per conversion. The CPC calculator covers the first part.
Update history
New features, fixes and data refreshes for this tool, newest first.
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· v1.0
LaunchedFirst release.
Missing something or found an error? Tell us — requests that come up often go into the next update. All tool updates
Count conversions where they happen
Connect your site and every tagged campaign shows its conversions and revenue, ready to set against what it cost.