This calculator helps you determine your cost per acquisition (CPA), one of the most important metrics in paid advertising. CPA shows how much you spend to generate a customer, lead, or conversion.
It is widely used across Google Ads, Facebook Ads, TikTok Ads, ecommerce campaigns, and lead generation funnels. If your CPA is too high, scaling spend can increase losses even when campaign revenue looks strong.
Understanding CPA is critical because ad performance should not be judged on clicks or impressions alone. What matters is whether the acquisition cost stays below your profit per sale or lifetime customer value.
The result shows how much you pay for each conversion. For example, a CPA of £25 means every customer or lead costs £25 in advertising spend.
This number becomes meaningful when compared with your gross profit, contribution margin, or customer lifetime value. A low CPA can support profitable scaling. A high CPA can quickly make campaigns unsustainable.
CPA = Ad Spend ÷ Conversions
The calculator divides total spend by the number of conversions generated. This gives you the average cost of each acquisition, making it easier to compare channels, campaigns, audiences, or landing pages.
CPA is especially useful when deciding whether an ad campaign is worth scaling, pausing, or rebuilding.
CPA should never be viewed in isolation. The most important question is whether your CPA is below your profit per sale or break-even acquisition threshold.
For example, if you earn £18 profit per order before advertising and your CPA is £22, then every sale generated through ads loses money. If your CPA is £10, then the campaign may be scalable assuming returns, VAT, and fees are already accounted for.
Strong businesses monitor CPA alongside ROAS, margin, and unit economics. Together, these metrics show whether growth is genuinely profitable or only looks good on the surface.
Example 1: £250 spend ÷ 10 conversions = £25 CPA
Example 2: £180 spend ÷ 12 conversions = £15 CPA
Example 3: If profit per order is £20 and CPA is £28, the campaign is unprofitable unless repeat purchase value closes the gap.
The cost to acquire one customer, lead, or conversion.
Divide ad spend by total conversions.
It shows whether your advertising cost stays below your profit per acquisition.