Marketing returns
Cost per Action Calculator
Measure advertising cost per attributed lead, signup, purchase, or other explicitly defined conversion action.
Use CPA for cost per tracked action, including actions from existing customers. Use CAC for fully scoped spending per newly acquired customer.
What the result means
CPA is the average cost for the chosen action. A low cost per lead is not necessarily a low cost per customer, and repeat-customer purchases must not be silently treated as new acquisitions.
The formula
Campaign spend / attributed actions
Results are displayed to at most two decimal places. Calculations use the unrounded inputs.
A worked example
Put the formula to work
- Campaign spend (currency)
- 2,400
- Attributed actions (actions)
- 80
CPA (input currency per attributed action): 30.00
A campaign spending 2,400 for 80 attributed qualified leads has a CPA of 30 per lead.
How to use this calculator
- Choose one conversion action and state its qualification rules.
- Count attributed actions using a consistent attribution window.
- Divide matching campaign spend by that action count.
- Evaluate action quality or downstream sales before changing budget.
Why this number matters
CPA turns campaign outcomes into a unit cost while keeping the event definition visible, so a cheap low-value action is not mistaken for efficient customer acquisition.
Input definitions
- Campaign spend (currency)
- Spending assigned to the campaign and conversion window used in the action count.
- Attributed actions (actions)
- Count of one defined action, such as qualified leads or purchases; do not combine unlike conversion types. Must be greater than zero.
Assumptions and limitations
- The same person may complete multiple counted actions.
- Includes only the spend supplied, not automatically sales labor or other acquisition costs.
- Attribution overlap and conversion lag can distort period comparisons.
Methodology
The default result and worked example use the same calculation functions as the interactive tool. The formula cannot verify the quality or scope of your source data.
Read our calculation methodology
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