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How many months before a customer has paid back what you spent to win them.
Payback is the cash-flow constraint on growth in a way the LTV:CAC ratio is not. A business can have excellent unit economics and still be unable to grow, because every new customer ties up cash for a year before returning any of it.
Used to estimate cash tied up in acquisition
Payback is measured on gross profit, not revenue. Using revenue makes the period look shorter than the cash reality, which is how businesses talk themselves into spending they cannot fund.
Under twelve months means each customer funds the next one within a year. That is the threshold at which growth can largely finance itself, and it is why 12 months is the benchmark everyone quotes.
Payback at other margins
Gross margin moves payback almost as much as CAC does. Worth confirming yours before assuming acquisition is the problem.
A $50 customer at an 80% margin returns $40 a month, not $50. Using revenue makes a $400 CAC look like an eight-month payback when it is really ten. The difference compounds across every customer you acquire and it is always in the optimistic direction.
| Method | Monthly return | Payback |
|---|---|---|
| On revenue | $50.00 | 8.0 months |
| On gross profit at 80% | $40.00 | 10.0 months |
| On gross profit at 65% | $32.50 | 12.3 months |
| Segment | Payback |
|---|---|
| Self-serve / SMB | Under 6 months |
| Mid-market | 6–12 months |
| Enterprise | 12–18 months |
| Any bootstrapped business | As short as possible |
The enterprise figure is tolerable only because contracts are long and retention is high. A short payback matters far more when you have no outside capital, because the customers themselves are funding the next ones.
Annual billing is the most underused of these. It does not change LTV or the ratio at all — it changes when the cash arrives, which is the entire constraint.
GOOD QUESTIONS
Under 12 months is the general benchmark, and under 6 is strong for self-serve SMB products. Enterprise businesses tolerate 12–18 months because contracts are longer and retention is higher. Bootstrapped companies should aim as short as possible, since customers fund growth.
Gross profit. Revenue ignores the cost of serving the customer, which makes payback look shorter than the cash reality. At an 80% margin the difference is 25% — enough to change a funding decision.
Dramatically. Collecting twelve months up front means a customer repays their acquisition cost almost immediately. It does not change LTV or the LTV:CAC ratio, but it removes the cash constraint that actually limits growth.
Because the ratio ignores time. A 4:1 ratio with a twenty-month payback still means every customer ties up cash for nearly two years. The ratio tells you whether to grow; payback tells you how fast you can afford to.