CPA Calculator
Calculate cost per acquisition/action, or solve for cost or conversions from the other two — with clear notes on how it differs from CPC and ROAS.
Conversions can be a decimal here — ad platforms often report fractional conversion counts when attribution is split across multiple touchpoints.
CPA (cost per acquisition/action) is what you pay for each completed conversion — a purchase, signup, or lead — not each click. It is a different metric from CPC (cost per click, which happens before any conversion) and from ROAS (which compares spend to revenue, not to a count of conversions). There is no universal "good" CPA — what counts as acceptable depends entirely on your margin and customer lifetime value.
Calculated entirely in your browser — nothing you enter here is sent to a server.
CPA (cost per acquisition, sometimes called cost per action) is what you pay for each completed conversion — a purchase, signup, or qualifying lead — CPA = Cost ÷ Conversions. Unlike CPC, which is charged the moment someone clicks, CPA reflects what actually happened after the click.
Conversions accepts a decimal value here, since ad platforms using data-driven or estimated attribution routinely report a fractional conversion count when credit for one conversion is split across multiple touchpoints — that's real reported data, not an input mistake.
How to use the CPA Calculator
- Under What do you want to calculate?, choose Solve for CPA, Solve for cost, or Solve for conversions.
- Enter the two values the mode asks for, such as Cost ($) and Conversions.
- Click Calculate to see the result: money with two decimals, conversions as a whole number.
- Click Reset to clear the inputs before running another scenario.
Example: CPA with fractional conversions
Choose Solve for CPA, enter 1250 as Cost ($) and 37.5 as Conversions, then click Calculate. The result is $33.33, since 1250 ÷ 37.5 is 33.333..., which the display rounds to two decimals.
Questions about the CPA Calculator
- How do I find how many conversions a budget will buy at a target CPA?
- Choose Solve for conversions and enter your target CPA and the budget as Cost. A $45 CPA and $2,000 cost gives 44 conversions, the whole number the budget fully pays for, with a note that the exact result is 44.44.
- Can I use a currency other than US dollars?
- Yes. The calculation is plain division and multiplication, so any currency works as long as cost and CPA use the same one. The result is always labeled with a $ sign regardless.
- Which inputs are rejected?
- Negative values are rejected in every mode. Solve for CPA needs conversions above zero, and Solve for conversions needs a CPA above zero; a cost of zero is accepted and simply gives zero.
- What should I enter as cost?
- Enter the total spend for the same period and campaigns that produced the conversions you count. Mixing a monthly spend with a weekly conversion count will give a misleading CPA.