CAC Payback Period Calculator

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Illustrative calculation; verify inputs and assumptions before relying on it.

CAC Payback (months)—

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CAC Payback Period = CAC / (Monthly ARPA × Gross Margin)
Variable Meaning
CAC Customer acquisition cost.
Gross Margin Gross margin percentage on recurring revenue.
Monthly ARPA Average revenue per account per month.

Worked example

CAC
$6,000
Monthly ARPA
$1,000
Gross Margin
80%
→ CAC Payback (months)
7.5

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What CAC Payback Period measures

Published by 4NLab · Updated · Our methods

CAC payback period estimates the number of months needed for a customer’s gross profit contribution to recover the cost of acquiring that customer.

Prepare your inputs

  1. Use fully loaded CAC for the customer segment you want to evaluate.
  2. Estimate monthly recurring revenue per account and its gross margin. Enter an 80% margin as 80 in the calculator.
  3. Divide CAC by monthly ARPA multiplied by gross margin. Check the simplified result against a month-by-month cohort contribution schedule when prices or costs change over time.

Formula

CAC Payback Period = CAC / (Monthly ARPA × Gross Margin)
Variable Meaning
CAC Customer acquisition cost.
Gross Margin Gross margin percentage on recurring revenue.
Monthly ARPA Average revenue per account per month.

Check the sample calculation

Worked example

CAC
$6,000
Monthly ARPA
$1,000
Gross Margin
80%
→ CAC Payback (months)
7.5

Before using the result

  • The steady-state model assumes the customer remains active and contribution stays constant until recovery.
  • Use the same cost and customer scope for CAC, ARPA, and margin.
  • A zero or negative monthly gross profit provides no finite payback under this model.

A dash means the result is undefined for the inputs, such as division by zero. Review the assumptions and input errors before interpreting it.

Read the CAC Payback Period guide for a business scenario, interpretation, and frequently asked questions.

Check how your team defines CAC Payback Period before relying on the result.

Sources and methodology

The references below explain the underlying methods. Our worked scenarios use hypothetical figures; they are not company results or current market benchmarks.

Found an error or a definition that differs from your reporting? Send a correction with the page URL and the method you use.