Growth calculator
CAC Payback Calculator
Estimate how long it takes to recover customer acquisition cost from monthly gross profit after support and payment processing costs.
Results
Results are deterministic scenario outputs, not guarantees.
Enter values and calculate to see the summary, supporting metrics, warnings, and interpretation.
Interpretation
Deterministic interpretation rules will explain what the modeled result means once a calculation is available.
Detailed breakdown
Intermediate calculation rows will appear here after calculation.
Formula
Monthly gross profit
monthlyGrossProfit = monthlyRevenuePerCustomer × (grossMarginRate - paymentProcessingRate) - supportCostPerCustomerPerMonth
Net CAC
netCAC = cac - onboardingRevenue × onboardingGrossMarginRate
Simple payback
paybackMonths = netCAC / monthlyGrossProfit
Active customer probability
activeCustomerProbability(month) = (1 - monthlyChurnRate) ^ (month - 1)
Expected gross profit by month
expectedGrossProfit(month) = activeCustomerProbability(month) × (monthlyRevenue(month) × (grossMarginRate - paymentProcessingRate) - supportCostPerCustomerPerMonth)
Assumptions
- Monthly revenue, support costs, churn, and expansion are entered as deterministic scenario assumptions.
- Onboarding gross profit reduces CAC before payback is calculated.
- Payment processing is modeled as a revenue percentage before support costs are subtracted.
- Outputs describe modeled CAC recovery bands, not forecasts or guarantees.
Worked example
Example: CAC payback
If CAC is $1,200, monthly revenue is $250, gross margin is 75%, processing is 3%, and support costs are $25, monthly gross profit is $155 and simple payback is about 7.7 months before churn or expansion effects.
FAQ
What is CAC payback?
CAC payback is the modeled time required for customer gross profit to recover the acquisition cost for that customer.
Why does churn affect payback?
Churn reduces the probability that the customer is still active in later months, so expected future gross profit is discounted by active customer probability.
Are the payback bands universal benchmarks?
No. The bands are deterministic capital-recovery ranges; acceptable payback depends on business model, capital availability, retention, and growth goals.