SaaS Metrics

CAC Payback Period Calculator

Estimate how many months it takes to earn back customer acquisition cost.

Payback period = CAC / Monthly gross profit per customer

What this calculator does

Estimate CAC payback months by dividing acquisition cost per customer by stable monthly gross profit per customer.

Scope, period, and currency

This page runs a local formula from user-entered values. The country/currency selector changes money symbols and formatting only: it does not perform live or historical FX conversion or automatically change contract, tax, accounting, or regulatory rules. Convert all amounts into one currency first and keep periods and metric definitions consistent.

Formula variables

C: Customer acquisition cost.
G: Monthly gross profit per customer after cost of service.

Formula and worked example

Formula: Payback months = C ÷ G.

Recalculation: $190 CAC ÷ $32 monthly gross profit = 5.94 months, approximately 178 days using the page's 30-day month convention.

Model assumptions

Monthly gross profit is positive and stable.
Revenue timing, churn, expansion, discounting, and collection delays are excluded.
The day estimate uses 30 days per month.

Reading the result and model boundary

A shorter modeled period recovers CAC faster under the entered assumptions.
If the customer churns before cumulative gross profit reaches CAC, acquisition cost was not recovered.

This is a steady monthly gross-profit model, not a cohort cash-flow schedule.

How to use it

Calculate CAC under a documented cost scope.
Calculate monthly revenue less cost of service for the same customer segment.
Divide and compare the result with observed cohort retention.

Common incorrect uses

Using revenue instead of gross profit.
Assuming every customer survives through payback.
Applying one universal healthy-month threshold to every business.

Suggested verification workflow

Align CAC and gross-profit cohort.
Calculate payback.
Test churn, margin, and collection timing.

FAQ

Should I use revenue or gross profit?

Use monthly gross profit after cost of service for a margin-aware payback estimate.

Does payback account for churn?

No. Compare the result with cohort survival separately.

Does currency selection convert CAC?

No. It changes formatting only; CAC and gross profit must use one currency.

Method and review boundary

Results are calculated locally in the browser from the formula shown on this page. The tool does not retrieve live rates, quotes, approvals, or billing data. Last reviewed: July 24, 2026.

Use the result for first-pass estimates, scenario comparison, and question preparation; it is not financial, investment, tax, accounting, or legal advice.

Authoritative sources and notes

CAC payback period - Stripe
Customer acquisition cost in SaaS - Stripe
IFRS 15 Revenue from Contracts with Customers - IFRS Foundation

Sources checked July 24, 2026. Rates, product rules, and official guidance can change; verify them again before a formal decision.