CAC Payback Period
The CAC payback period is the number of months of gross profit from a new customer needed to recover the cost of acquiring them. It is the cash-efficiency metric: shorter payback means growth funds itself sooner.
Formula
Worked example
CAC of $1,800 against $150/month ARPU at 75% gross margin is $1,800 ÷ $112.50 = 16 months to break even on the acquisition.
Payback matters most when capital is expensive: an 8-month payback lets you recycle cash into acquisition three times faster than a 24-month payback. Efficient SMB SaaS runs under 12 months; enterprise motions tolerate 18–24 because retention is higher and contracts are annual-prepaid.
Use gross profit in the denominator, not revenue — a customer paying $150 only returns $112.50 of margin at 75% GM, and that is what actually repays the CAC.
Compute it: CAC payback calculator