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Marketing

Cost Per Acquisition Calculator

Calculate the average cost per acquisition from campaign spend and the acquisitions it produced.

Enter total campaign spend and the number of acquisitions in the same period.

Enter your values

Spend for the campaign over the measurement period.

$

Conversion events credited to the same campaign and period.

acquisitions

Results

Cost per acquisition

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Enter campaign spend and acquisitions.

Total campaign spend

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The spend figure entered.

Acquisitions

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The acquisitions entered.

Results are estimates based on the values entered and are provided for general planning.

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Step by step

How to use the CPA

  1. Enter the Total campaign spend for the period.
  2. Enter the Acquisitions credited to the same campaign and period.
  3. Read the average cost per acquisition.

Method

How to calculate CPA

CPA divides what a campaign cost by how many acquisitions it delivered, giving the average price paid for each one. Because it is an average, it flattens variation between channels, audiences, and creatives inside the same campaign.

Formula

CPA = Total campaign spend ÷ Acquisitions

Assumptions

  • Spend and acquisitions cover the same campaign and the same time period.
  • An acquisition is whatever conversion event your business is counting.
  • Acquisitions is a positive whole number, because dividing by zero acquisitions has no defined cost.
  • Only the spend entered is included — creative, agency, and tooling costs are excluded unless you add them.

The division is calculated at full precision before display. Currency displays two decimals; acquisitions display as whole numbers.

How to interpret the result

CPA tells you the average price of a conversion under the spend you entered. It does not tell you whether that price is affordable — that depends on what an acquisition is worth to you. Compare CPA against the revenue or margin a converted customer generates before drawing conclusions.

Worked example: comparing two channels

Search ads spend $3,600 and produce 90 trial sign-ups, a $40.00 CPA. Social ads spend $2,400 for 40 sign-ups, a $60.00 CPA. Combined, $6,000 ÷ 130 = $46.15. The blended figure hides that one channel costs 50% more per sign-up.

When to use it: checking against what an acquisition is worth

Compare CPA with the gross profit each acquisition brings. If a sign-up is worth $50 of gross profit, search earns $10 per acquisition while social loses $10. Define one acquisition the same way across channels before comparing.

CPA vs CAC

The two metrics are often used interchangeably, and often incorrectly. CPA typically answers 'what did this campaign pay for each conversion event?' CAC typically answers 'what did the business pay, across all acquisition activity, for each new paying customer?'

The gap between them matters. A campaign can report a $25 CPA on free-trial signups while the business CAC per paying customer is several times higher, because only a fraction of trials convert and CAC also carries salaries, tooling, and channels the campaign never touched.

What moves CPA

CPA is the product of two things: how much traffic costs and how well that traffic converts. It can fall because clicks got cheaper or because the landing page converted better — the number alone does not tell you which.

Separating CPC from conversion rate is usually more actionable than watching CPA move on its own.

Frequently asked questions

Whatever conversion event your business has defined: a purchase, a paid signup, a qualified lead, a subscription start, or a booked call. The number is only meaningful if you keep that definition consistent.

Not universally. CPA is usually campaign-level and counts whatever conversion event was defined, which may not be a paying customer. CAC is usually business-level and counts new paying customers against broader sales and marketing spend.

Dividing spend by zero acquisitions has no defined answer. If a campaign spent money and produced nothing, the honest statement is that it produced no acquisitions — not that CPA is infinite.

Include them if you want CPA to reflect the full cost of acquisition. Just be consistent: comparing a media-only CPA against a fully loaded CPA will mislead you.

Yes, if spend was zero and acquisitions still occurred — organic conversions attributed to a campaign with no media cost, for example. The calculator accepts zero spend.

Which calculator do you need?

  • Need total acquisition cost including all sales and marketing spend? Use the CAC Calculator.
  • Want the revenue returned per ad dollar? Try the ROAS Calculator.
  • Looking at the click costs that drive acquisition? Use the CPC Calculator.
  • Not sure whether CPA or CAC fits your question? Read CAC vs CPA.

Keep calculating

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