CAC Payback Period Calculator
Written by Thierno Sadou Diallo, formula verified per our methodology • Last checked on 9/10/2026
The CAC payback period is calculated with CAC ÷ (monthly revenue per customer × gross margin). For a €300 CAC, €50/month revenue, and 80% gross margin, it takes 7.5 months to pay back a customer's acquisition.
Explanation
Acquiring a customer costs money (advertising, sales team, referral bonuses) before they generate anything. The CAC payback period measures the number of months needed for the gross margin a new customer generates to offset that initial acquisition cost. It's a cash-flow metric: the shorter this period, the less the business needs to fund the gap between the acquisition spend and the gradual return, and the faster it can reinvest in the next acquisition. This calculator builds on the same customer acquisition cost figure but adds the time dimension the LTV:CAC ratio leaves out: two businesses can have the same 3:1 LTV:CAC ratio while having very different payback periods (6 months for one, 24 for the other), with radically opposite funding needs. The benchmark commonly cited in the venture capital ecosystem puts a healthy period below 12 months for a SaaS business, but this threshold varies by sector, contract size, and the company's funding capacity. The calculation uses gross margin rather than total revenue, because it's the direct costs of delivering the service (hosting, support) that actually eat into a customer's return — gross margin is also the basis of our customer lifetime value calculator.
Example: €300 CAC, €50/month revenue, 80% margin
Inputs
Customer acquisition cost: €300. Monthly revenue per customer: €50. Gross margin: 80%.
Calculation
Monthly gross margin per customer = 50 × 80% = €40. Payback = 300 ÷ 40 = 7.5 months.
Result
It takes 7.5 months for a new customer to pay back the €300 spent to acquire them.
Frequently asked questions
Why use gross margin and not total revenue in the calculation?
Because the revenue a customer generates isn't fully available to repay the acquisition cost: part of it covers the direct costs of delivering the service (servers, bandwidth, customer support, third-party licenses). Only gross margin — revenue minus these direct costs — actually contributes to paying back the CAC. Using total revenue would give an artificially optimistic period.
How does this differ from the LTV:CAC ratio?
The LTV:CAC ratio compares the total value a customer generates over their entire lifetime to their acquisition cost, with no notion of time: it tells you whether the acquisition is profitable in the long run. The payback period tells you when it becomes so. A business can have an excellent LTV:CAC ratio but a payback period so long that it runs out of cash to fund its growth in the meantime.
Is a payback period over 12 months a dealbreaker?
No, it's only an indicative benchmark from the venture capital ecosystem, most relevant for SaaS businesses with small contracts and high growth. Companies selling large contracts to enterprise accounts, with long sales cycles but near-total retention, commonly accept 18 to 24-month periods, provided they have the funding to absorb that gap.