Free tool

Payback Period Calculator

How long until a customer pays you back?

This payback period calculator shows how many months it takes to earn back a customer acquisition cost or any upfront spend, using gross margin and, if you want, monthly churn. Works in dollars, pounds or euros.

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Your numbers

Currency

Upfront cost (CAC or investment)

Monthly revenue per customer

Gross margin

Monthly churn (0 to ignore)

You earn it back in

Payback period

15 months

Gross profit per month

$40.00

Lifetime gross profit

No churn entered

Years

1.25

Estimate only. Uses average monthly gross profit per customer and a constant monthly churn rate; real cohorts vary.

Key takeaways

Payback months = upfront cost ÷ monthly gross profit, where gross profit = revenue × gross margin.
Example: $600 to win a customer paying $50 a month at 80% margin earns $40 a month, so payback is 15 months.
Under 12 months is a common target for self-serve SaaS; over 24 months needs very low churn.
With churn, later months earn less, so the same example with 3% monthly churn takes about 19.6 months, and above 6.7% churn it never pays back.

Hustlay project cards with profit and margin per project — Hustlay shows each project's margin, the input you need for an honest payback period.

Payback depends on real costs and real margin. Hustlay tracks both per project, with shared costs split.

Track margin per project

How it works

From acquisition cost to payback months

Monthly gross profit = monthly revenue per customer × gross margin.
Payback (no churn) = upfront cost ÷ monthly gross profit.
Payback (with churn c): after n months a customer has earned gross profit × (1 − (1 − c)^n) ÷ c, and payback is the n where that equals the cost.
Never pays back when cost × c ÷ gross profit is 1 or more, because lifetime gross profit (gross profit ÷ c) is below the cost.

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