CPA Calculator
CheckedUse this CPA calculator to find your cost per acquisition and the highest CPA your margin can afford before every order loses money. Free, no sign-up, and the result updates as you type.
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A CPA is only high or low relative to what one customer is worth, and the worth is gross profit, not order value. A $50 CPA on a $120 order sounds comfortable until the 38% margin on that order turns out to be $45.60, at which point every acquisition loses $4.40 and the campaign scales the loss. This calculator reports the CPA you are paying and the maximum CPA your margin can carry, so the gap between them is a dollar figure rather than a feeling.
How it's calculated
CPA = ad spend ÷ conversions Max CPA = average order value × gross margin
LaTeX source
\text{CPA} = \frac{S}{C} \qquad \text{Max CPA} = \text{AOV} \times m Worked examples
A campaign with room to bid harder
$30.00 CPA against a $42.75 ceiling
$2,400 over 80 conversions is a $30.00 CPA. A $95 order at a 45% gross margin yields $42.75 of gross profit, so each acquisition nets $12.75 and there is 29.8% headroom before break-even. That headroom is the case for raising bids: volume bought at anything under $42.75 still adds profit, even as CPA rises.
The numbers used
- Ad spend
- 2400
- Conversions
- 80
- Average order value
- 95
- Gross margin
- 45
A campaign already over the line
$50.00 CPA against a $45.60 ceiling
$5,200 over 104 conversions is a $50.00 CPA. At a 38% margin a $120 order carries $45.60 of gross profit, so the campaign is $4.40 underwater per acquisition and 9.6% past its ceiling. Across 104 orders that is $458 of loss, hidden inside a dashboard reporting a perfectly normal 2.40× ROAS.
The numbers used
- Ad spend
- 5200
- Conversions
- 104
- Average order value
- 120
- Gross margin
- 38
Questions sellers ask
How do you calculate CPA?
Divide total ad spend by the number of conversions it produced. $2,400 of spend and 80 orders is a $30.00 CPA. Keep the numerator and denominator on the same window and the same attribution setting, because a 7-day click window and a 1-day window will not report the same conversion count for identical spend. Then compare the result against gross profit per order, not order value.
What calculator can you use on CPA?
On the CPA exam you can use only the four-function calculator built into the exam software, because NASBA's candidate guide bars personal calculators from the testing room. The exam software also includes a spreadsheet tool. This page is about a different CPA, cost per acquisition in advertising, which any calculator can work out by dividing ad spend by conversions.
What is a good CPA?
A good CPA is any CPA below the most an order can afford, which is average order value multiplied by gross margin, so there is no single good figure. A $95 order at a 45% margin can carry up to $42.75 of ad cost. At a $30.00 CPA that leaves $12.75 of profit per acquisition, 29.8% under the ceiling. Use the margin left after goods, fees and shipping, or the ceiling comes out too high.
What is the CPA equation?
CPA = total ad spend ÷ total conversions. Two useful rearrangements follow from it: conversions = spend ÷ CPA, which sizes a budget against a volume goal, and max CPA = average order value × gross margin, which sets the ceiling. You can also reach CPA from click data as CPC ÷ conversion rate, so a $1.25 CPC at a 3.2% conversion rate implies a $39.06 CPA.
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