Canonical formula calculator
SERVICE BUSINESSES — CAC PAYBACK PERIOD
How many months until a new customer pays back what it cost to acquire them. For service businesses, the picture has its own shape — see the industry context below.
Worked example
How the number is worked out
The same customer, and the question the ratio cannot answer: how long until the money is back.
Starting from
Working
Six months before a customer has repaid what it cost to win them. Until then every new customer makes this month’s cash position worse, not better — which is how a growing business runs out of money.
What this tells you
Service businesses should see CAC payback inside the FIRST customer transaction for most categories — emergency HVAC, dental cleaning, salon visit. If you're paying months to recover acquisition cost on a service customer, you either have a CAC discipline problem (Google Ads efficiency, lead source quality) or a pricing problem (your service is underpriced relative to the cost of getting one new customer to book it). CAC payback period is the months between paying to acquire a customer and recouping that cost from their recurring contribution. Shorter payback = healthier business + lower capital requirement. Investors and operators watch this signal because it accounts for both unit economics and gross margin in one number.
When to use it
Industry benchmark — Healthy service-business CAC payback: First transaction. Check this monthly alongside CAC and LTV. Use it especially when deciding whether to raise or scale acquisition spend — a short payback means you can reinvest faster; a long payback means you are betting on retention you may not get.
What it doesn’t tell you
CAC payback is a one-cohort lens. It does not capture expansion revenue, NRR > 100% dynamics, or whether retention curves are improving cohort-over-cohort. A 12-month payback that is trending up is a different reality than a 18-month payback that is trending down.
Reckon it, don’t just calc it
A calculator gives you today’s number. Reckon takes your plan to make your own money and checks it against what’s real — your margin, your price, what it takes to hit the take-home you want. No AI, no guessing — the same input always gives the same answer.