payback: definition
The time it takes for a customer to pay back what it cost you to acquire them. The shorter it is, the faster you can reinvest.
By Mathéo Ballasse · June 18, 2026
Definition
Payback (or payback period) measures, in months, the time needed to recover the CAC through customer revenue. It is as much a cash metric as a profitability one: a short payback frees up cash to fund the next wave of acquisition. In B2B SaaS, a return under twelve months is often the target; beyond that, growth eats too much cash.
How to calculate it
Payback (in months) = CAC / average monthly revenue per customer
Why it matters
Two channels can have the same LTV but very different paybacks: one that pays you back in three months lets you reinvest far faster than one that takes a year. Payback therefore determines how fast you can grow without running out of cash.
When to use it
You look at it mainly when cash is tight and you are choosing where to put the budget. In practice, with limited runway, you favor channels with a short payback, even if it means sacrificing a bit of LTV, so you do not tie up your cash for too long.
Example
A CAC of 600 euros and a subscription at 100 euros a month give a payback of six months.
Common mistakes
- Confusing it with LTV: speed of return versus total value.
- Ignoring the cash constraint it reflects.
- Calculating it on revenue instead of margin.
Don't confuse it with
- ltv: Payback measures how fast you recover the CAC; LTV measures the customer's total revenue, with no notion of timing.
Related terms
Articles that use this term
Frequently asked questions
- What payback should a SaaS aim for?
- In B2B, a CAC payback under 12 months is a good benchmark; very efficient SaaS companies get it under 6 months.