CPA Calculator (Cost Per Acquisition)

CPA (cost per acquisition) is what you pay in ad spend for one conversion, such as a purchase or a lead: spend divided by conversions. This free CPA calculator works it out from two numbers and, if you add price and variable costs, shows your break-even CPA, the most one order can cost before it loses money.

Free, no sign-up. Runs in your browser.

Product cost, shipping, payment fees, anything paid per order.

Results

CPAcost per purchase
$50.00
Break-even CPAThe most you can pay for one order without losing money.
$60.00
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How do you use the CPA calculator?

Enter ad spend and conversions for the same ads and date range. The calculator shows CPA straight away; add price and variable costs to see break-even CPA next to it.

  1. In your ad account, set the date range and select the campaigns.
  2. Copy amount spent and the number of conversions you want to measure (purchases, leads, sign-ups).
  3. Optional: enter price per order and variable costs per order for break-even CPA.
  4. Copy the page link to share the result. Only the numbers are stored in it.

What is the CPA formula?

CPA is spend divided by conversions. Meta calculates cost per website purchase as total spend divided by website purchases.

CPA = ad spend ÷ conversions
CPA = CPC ÷ conversion rate
Break-even CPA = price − variable costs per order

The second line is the same result reached through clicks. The Amazon Ads "Ads Math" guide uses it as "CPC ÷ conversion rate = CPA", and compares CPA with profit per sale to find net profit or loss per sale.

Worked example

Enter these numbers in the calculator above (example numbers, in any currency):

Input Value
Ad spend 2,500
Purchases 50
Price per order 150
Variable costs per order 90

The tool shows the same results:

Output Working Result
CPA 2,500 ÷ 50 50
Break-even CPA 150 − 90 60

Check it through clicks: with 3,000 clicks, CPC is 2,500 ÷ 3,000 = 0.83 and conversion rate is 50 ÷ 3,000 = about 1.67 percent. Then 0.8333 ÷ 0.01667 = 50, the same CPA.

In this example the CPA (50) is below the break-even CPA (60), so each first order covers its ad cost and leaves 10 of margin. If CPA rises above 60, the ads need a lower CPC or a higher conversion rate, or the product needs a higher margin per order.

Which conversion should you count?

Count the conversion that pays you. For an online store that is a purchase; for a service business it is usually a lead or a booked call.

Conversion CPA name often used Compare it with
Purchase Cost per purchase Break-even CPA (contribution margin per order)
Lead Cost per lead Value of a lead: close rate × margin per sale
Add to cart or sign-up Cost per add to cart, cost per sign-up Only useful as an early signal, not for profit

A cost per add to cart can look cheap while the cost per purchase is too high. When you report CPA, name the conversion next to the number, for example "CPA (purchase) 50".

In Meta Ads Manager, the purchase count is in the Purchases column (or Website purchases), and Meta also shows its own Cost per purchase column. If your number and Meta's differ, check that the date range and attribution setting match.

What changes CPA?

CPA has two parts: what a click costs and how many clicks convert. Each points at a different fix.

If this is high Look at
CPC (from a high CPM or a low CTR) The ad: hook, format, offer in the first seconds
1 ÷ conversion rate (few clicks convert) The landing page, price and offer

The CTR calculator and CPM calculator split CPC into its parts. For video ads, the hook rate calculator shows how many impressions turned into a 3-second play, the step before any click.

What are the limits of this calculator?

The calculator divides spend by conversions. It can't tell which conversions the ads caused.

  • Attribution. Conversions are what the ad platform attributes under its setting. Your own analytics may count more or fewer.
  • Repeat buyers count. CPA includes purchases from existing customers. For new customers only, use the CAC calculator.
  • First order only. Break-even CPA covers one order. If customers reorder, the LTV calculator shows what they are worth over time.
  • No benchmarks. CPA depends on price, category and country, so the tool shows no "good" or "bad" verdict.

See the CPA glossary entry, the CAC entry and the contribution margin entry. The break-even ROAS calculator gives the same limit as a ROAS figure, and the ad metrics calculator shows CPA with every other ratio. All free tools are on the tools page.

If you want more ad creative to bring CPA down, see how Anglr works for brands.

Glossary: CPA · CAC · Contribution margin

FAQ

How do you calculate cost per acquisition?

Divide ad spend by the number of conversions in the same period. Spending 2,500 for 50 purchases gives a CPA of 50.

What is the difference between CPA and CAC?

CPA counts every conversion, including repeat purchases by existing customers. CAC counts only new customers and often includes more than ad spend, so CAC is usually the higher number.

What is break-even CPA?

It is your contribution margin per order: price minus all variable costs per order. A product selling for 150 with 90 in variable costs has a break-even CPA of 60.

Is CPA the same as cost per result in Meta Ads Manager?

It is when the result is the conversion you care about. Cost per result divides spend by whatever result the campaign optimises for, so check that the result is purchases (or leads) before reading it as CPA.

How do CPC and conversion rate give CPA?

CPA equals CPC divided by conversion rate. A CPC of about 0.83 with a conversion rate of about 1.67 percent gives a CPA of 50.

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Sources

Checked: 12 Oct 2026