CPA = ad spend ÷ conversionsHow to use this calculator
- Decide which conversion action you are measuring, such as a lead or purchase.
- Enter spend and attributed conversions from the same reporting window.
- Switch to Ad spend or Conversions to model a target, then copy the result for your plan.
Worked example
An illustrative campaign spends $1,200 and records 40 purchases. CPA is $30. At that average cost, 100 purchases would require $3,000. If those 40 conversions were leads instead, the same arithmetic would be a $30 cost per lead, not a $30 cost per customer.
CPA, cost per action and cost per acquisition
CPA is used for the average advertising cost of a conversion action. That action might be a sale, lead, sign-up or install. Write the action beside the result so that a team reviewing lead generation does not mistake a lead CPA for purchase CPA.
CPA is not the same as CAC
This tool uses the spend you enter and the conversion count you choose. Customer acquisition cost commonly includes a wider set of sales and marketing costs and counts newly acquired customers. A campaign CPA based on all purchases does not automatically tell you the cost of acquiring a new customer.
Actual CPA versus target CPA
A target is a planning or bidding input. Actual average CPA comes from the spend and conversions recorded. Different attribution windows, conversion delays and counting settings can change that result. Let the conversion window mature before treating a short-term movement as a stable trend.
Reference: Google Ads: average CPA.
Common questions
How do I calculate cost per acquisition?
Divide the relevant spend by the acquisitions or conversions attributed to it. Keep the action, currency and reporting window consistent. The result is the average cost of that defined action.
Does the CPA calculator also calculate cost per lead?
Yes. Enter the number of leads as conversions. Label the output cost per lead. To work out cost per customer, use the number of customers acquired, or model the lead-to-customer conversion step separately.
Why does the calculator accept fractional conversions?
Attribution reports may assign partial conversion credit across interactions. Fractional credit can be appropriate if it comes from the same attribution model as your spend report. Do not round attributed credit just to make the calculation look simpler.
What if I spent money but had no conversions?
CPA is undefined with zero conversions. There is no finite average cost per conversion yet. The tool shows a validation message instead of presenting a zero CPA.