CAC Payback Period Calculator
How many months until a customer pays back what it cost to acquire them? Enter CAC, monthly ARPA and gross margin to get your payback period and how it compares to the 12-month bar.
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The CAC payback formula
CAC payback (months) = CAC ÷ (monthly ARPA × gross margin). The key detail is gross margin: you recover CAC out of gross profit, not revenue, because serving the customer has a cost. A $1,200 CAC against $120 ARPA at 80% margin is $96 of monthly gross profit, a 12.5-month payback, not the 10 months revenue alone would suggest.
Most SaaS investors want payback under ~12 months. SMB should aim lower (faster payback, since SMB churns more); higher-ACV and enterprise can tolerate 12–18+ months because those customers stay longer. The reason it matters: long payback strains cash, you fund acquisition today and wait months to get it back, so fast growth with slow payback burns money quickly.
Payback is one half of unit economics; pair it with the LTV:CAC ratio (is the customer profitable over their whole life?). See CAC payback period explained for benchmarks and how to improve it.
Plan the whole picture in Adlega
Adlega turns these one-off numbers into a live financial model for your SaaS, projections, scenarios, dashboards.