CPA Calculator

Written byOleh Soloninupdated 25 September 2026

Ad spend

Conversions

Revenue from those conversions

The total across all of them. For a ceiling that allows for cost of goods, enter the contribution margin of all those conversions.

Result

CPA$1,500.00
AssessmentRevenue covers the ad spend
Revenue per conversion3,000
Revenue less CPA per conversion1,500
Break-even CPA on revenue3,000
Conversions40

The metric decisions are made on

The cost of one conversion and whether the revenue that conversion brings actually covers it.

CPA shows what a target action costs: a lead, a signup, a purchase. Unlike CTR and CPC it already touches the business, and it is the number you hold against margin to decide whether to keep going.

The break-even CPA here is the revenue one conversion produces. Below it, revenue covers the ad spend — which is not yet profit, because cost of goods and other costs are not deducted. For a line that allows for them, enter contribution margin instead of revenue.

How to use

Enter ad spend and the number of conversions for the same period.
Add the revenue those conversions brought in — without it the calculator returns a CPA but cannot say whether revenue covers it.
Compare your CPA against the break-even figure, which is simply the revenue one conversion brings.
If a conversion is a lead rather than a sale, enter revenue adjusted for the share of leads that reach payment.

Where revenue stops covering the ad spend

Each row is a run of this calculator at 40 conversions and 120,000 of revenue, which is 3,000 per conversion. Only the ad budget changes.

The break-even CPA does not move: it equals revenue per conversion and has nothing to do with the budget. The verdict flips exactly where the CPA reaches that line — at a spend of 120,000 revenue less CPA per conversion is zero.

Runs of this calculator at 40 conversions and 120,000 of revenue.
Spend	CPA	Break-even CPA on revenue	Revenue less CPA	Verdict
40,000	1,000	3,000	2,000	Revenue covers the ad spend
60,000	1,500	3,000	1,500	Revenue covers the ad spend
90,000	2,250	3,000	750	Revenue covers the ad spend
120,000	3,000	3,000	0	Revenue covers the ad spend exactly
150,000	3,750	3,000	−750	Revenue does not cover the ad spend

What this calculator shows

Cost per conversion and the maximum you can afford
Revenue per conversion and what is left of it after the CPA
A direct verdict on whether revenue covers the ad spend

What to keep in mind

Revenue must come from those same conversions over the same period, or the comparison is meaningless.
For a break-even that allows for cost of goods, enter the gross profit of all those conversions rather than revenue.

FAQs

How does CPA differ from CPL?

CPL is the cost of a lead, a contact. CPA is usually measured on a deeper action — a paid order or a qualified enquiry. A campaign can show a CPL of 500 and a CPA of 3,000 if one in six converts.

How do I set a target CPA?

Take gross profit per conversion and subtract the profit you want to keep. If a conversion brings 3,000 of revenue at a thirty percent margin, the margin is 900 — paying more than that is working at a loss.

Why does CPA rise as I spend more?

The most relevant audience is bought first; after that the traffic gets colder. So doubling the budget does not necessarily double conversions, and extra spend is worth checking against the extra leads.

Should repeat purchases count?

Not when judging a single campaign, but certainly when judging the business. If customers return, the affordable CPA follows from lifetime value rather than the first sale, and it is far higher.

Why is the break-even CPA revenue rather than profit?

Because the calculator uses whatever revenue you type in. Enter gross revenue and the ceiling comes out too high, with cost of goods and delivery still to come. For an honest ceiling, put the contribution margin of all those conversions in the revenue field, not of one: 900 × 40 = 36,000, for example.

What happens with zero conversions?

The calculator returns an error: there is nothing to divide the spend by. That is not pedantry — CPA at zero conversions is infinite, and the conclusion to draw from such a campaign is not “expensive” but “not working at all”.

Worked example

A lead generation campaign

Input: 60,000 spend, 40 conversions, 120,000 revenue

Output: CPA 1,500 against 3,000 revenue per conversion — revenue covers it

Note: Fifteen hundred per lead against three thousand of revenue looks fine, but only above a fifty percent margin. At thirty percent a conversion yields 900 and the campaign is actually losing money.

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