Free tool · CPA
CPA Calculator
CPA — cost per action, or cost per acquisition — is what each conversion actually cost you to win. Enter any two of spend, actions, and CPA and this calculator solves for the third.
CPA tells you the price — not whether it was worth paying
The division is trivial. The judgement — was this action worth the spend? — depends on what the action is worth to you downstream.
Not every action is equal
A $20 CPA on a newsletter signup and a $20 CPA on a closed deal are not remotely the same buy. CPA prices the action you chose to count, so the metric is only as meaningful as the conversion definition behind it.
Cheap actions can still lose money
A low CPA looks efficient until you compare it to what the customer is actually worth. If your CPA creeps above the gross profit per acquisition, you are buying conversions at a loss no matter how cheap they look.
Attribution sets the count
CPA depends entirely on which conversions you credit to the spend. Last-click, view-through, and modelled attribution can each produce a very different action count — and therefore a very different CPA — from the same campaign.
Calculate your CPA
Enter any two of spend, actions, and CPA.
The full amount you spent (or plan to spend) on the campaign.
The number of actions you count as a conversion — signups, leads, purchases.
Cost per action — total spend divided by actions.
Waiting for input
Enter any two of total spend, actions, and CPA — the third fills in automatically.
Formula: CPA = total spend ÷ actions. Leave one field blank to solve for it.
What is CPA?
CPA stands for cost per action — also called cost per acquisition — and measures the average spend required to drive one conversion. The action can be anything you treat as a win: a lead, a signup, an install, or a purchase.
Because it ties spend directly to outcomes rather than to delivery, CPA is the bridge between media efficiency and business results. It is the number you compare against the value of an acquired customer to decide whether a channel is profitable.
Calculate CPA
CPA = Total spend ÷ Actions
Spend $10,000 to drive 250 signups → CPA = 10,000 ÷ 250 = $40.00
Calculate actions
Actions = Total spend ÷ CPA
$10,000 budget ÷ $40 CPA = 250 actions
Calculate spend
Spend = CPA × Actions
$40 CPA × 250 actions = $10,000
How to use this CPA calculator
Three fields, one equation — fill in the two you know.
Enter the two values you have
Know your spend and actions? Get CPA. Know your target CPA and budget? Get the actions it should buy. Any two of the three solve the third.
Define the action precisely
CPA only means something when everyone agrees on what counts as an action. Pin down the exact conversion event before comparing CPA across campaigns or channels.
Compare CPA to acquisition value
A CPA is only good or bad relative to what the action is worth. Hold it against gross profit per customer (or your target payback) to know whether the spend is profitable.
What is the difference between CPA and CAC?
CPA usually prices a single defined action — a lead, signup, or purchase — against media spend alone. CAC (customer acquisition cost) is broader: it divides all sales and marketing cost, including salaries and tooling, by net new customers. CPA is a campaign-level efficiency metric; CAC is a business-level one.
What is a good CPA?
There is no universal benchmark — it depends entirely on what the action is worth. A useful target CPA is the gross profit you make per acquired customer, divided by your desired payback multiple. Any CPA below that ceiling is profitable; above it, you are buying conversions at a loss.
Why is my CPA higher than my CPC?
CPA is always at least as high as CPC, because not every click converts. The relationship is CPA = CPC ÷ conversion rate. A $2 CPC at a 5% conversion rate produces a $40 CPA — so improving landing-page conversion lowers CPA without touching the auction.
Should CPA include actions from organic or other channels?
No — to keep CPA honest, only count the actions you can fairly attribute to the spend in the calculation. Mixing in organic or cross-channel conversions deflates CPA and makes a campaign look more efficient than it is.
One metric is a number — Multiply connects them all
When every campaign metric, brief, and account signal lives in one AI operating system, you stop calculating in spreadsheets and start acting on the full picture. That's Multiply.