Cost Per Acquisition Calculator
Cost per acquisition turns raw marketing spend into a number you can act on: what does it actually cost to win one customer? It connects budget directly to outcomes, so you can compare channels, set bids, and judge whether a campaign pays for itself. Because CPA depends on both how cheaply you buy traffic and how well that traffic converts, this calculator also breaks out the conversion rate and the implied cost per click. Enter your total spend, the number of conversions, and the clicks or visits, and the tool returns CPA, conversion rate, and cost per click.
CPA formula
CPA = total marketing spend / conversions
Conversion rate % = (conversions / clicks) * 100
Cost per click = total marketing spend / clicks
CPA can also be expressed as cost per click divided by conversion rate, which shows why improving conversion lowers acquisition cost.
Using CPA
- Keep CPA well below the value a customer is worth over time.
- A widely used guide is a lifetime value to CPA ratio of at least 3 to 1.
- Raising conversion rate lowers CPA without buying more traffic.
- Compare CPA across channels to reallocate budget efficiently.
- Use consistent definitions of a conversion so comparisons stay fair.
Cost per acquisition: frequently asked questions
What is cost per acquisition?
Cost per acquisition (CPA), also called cost per action, is the average marketing cost to acquire one customer or conversion. It equals total campaign spend divided by the number of conversions. CPA is a core efficiency metric because it ties spending directly to results.
How is CPA calculated?
CPA equals total marketing spend divided by the number of acquisitions or conversions. For example, US$5,000 of spend producing 100 customers gives a CPA of US$50. Lower CPA means you are acquiring customers more cheaply for the same outcome.
What is a good cost per acquisition?
A CPA is good when it is comfortably below the value of a customer. A common guide is that customer lifetime value should be at least three times CPA. The right CPA depends entirely on your margins and how much each customer is worth over time.
What is the difference between CPA and CPC?
Cost per click (CPC) is the cost of a single ad click, while CPA is the cost of an actual conversion such as a sale or signup. CPA equals CPC divided by the conversion rate, so a low CPC with a poor conversion rate can still produce a high CPA.
How does conversion rate affect CPA?
Conversion rate is the share of clicks or visits that convert. A higher conversion rate spreads the same spend over more customers, lowering CPA. Improving the conversion rate is often a faster route to a lower CPA than cutting the cost per click.
Official sources
- U.S. Federal Trade Commission: Advertising and marketing guidance.
- U.S. Small Business Administration: Manage your finances.
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.