CAC Payback Period Calculator

Background.

Every new subscription customer starts out as a debt. The ads, sales calls and free trial are paid for up front, and the customer repays them a month at a time. CAC payback counts how many months that takes, and because the money has to be found before it returns, it largely decides how much cash a company burns to grow at a given pace. Bessemer Venture Partners uses it, rather than the LTV:CAC ratio, as its main gauge of sales and marketing efficiency.

The arithmetic is one division — acquisition cost over what a customer contributes each month — and most of the arguments are about what goes above and below the line. Below it, both David Skok and Bessemer use gross profit rather than revenue, because the slice of every subscription dollar that pays for hosting, support, payment fees and third-party licences is never available to repay anything. Divide by revenue and the payback shrinks by exactly the cost of revenue. Above the line, Skok counts sales and marketing expense, while Bessemer adds the part of customer success that drives renewals, upsells and cross-sells, which lengthens the figure for the same business.

The published formulas share a blind spot: they assume the customer is still paying when the cost is finally recovered. A $3,000 acquisition repaid at $96 a month takes 31.25 months, but at 5% monthly churn the average customer stays only 20. That is not a slow payback; the money never comes back. Adding your churn rate runs that check without altering the payback figure itself, so the number stays comparable with how everyone else reports it.

What is cac payback period calculator?

CAC payback period, sometimes called months to recover CAC, is customer acquisition cost divided by the monthly gross profit one customer generates. Bessemer's definition is the number of months needed to pay back upfront acquisition costs after the variable expense of serving that customer. It is a measure of cash timing, not of profitability, and neither GAAP nor any standards body defines it. The reference points come from investors: Skok reports that many of the best SaaS businesses recover CAC in 5–7 months, with 12 months as the long-standing guideline, while Bessemer sets targets of under 12 months for SMB, 18 for mid-market and 24 for enterprise, and reports an average of 15 months for companies at $1–10 million ARR.

How to use this calculator.

1. 01Run one customer segment at a time; self-serve and enterprise customers differ in cost, ARPA and churn, and a blend describes neither.
2. 02Leave "Recover the cost out of…" on Gross profit unless you are reproducing someone else's revenue-based figure.
3. 03Enter Customer acquisition cost as the period's total acquisition spend divided by the customers it won, with the same cost scope every period.
4. 04Enter ARPA and Gross margin for the same cohort; margin is revenue minus hosting, support, payment and licence costs.
5. 05Enter Monthly customer churn. It leaves the payback unchanged but drives the lifetime check behind the verdict.

The formula.

Monthly contribution = ARPA × gross margin on the standard basis, or ARPA alone on the revenue basis. Payback (months) = CAC ÷ contribution, which is Skok's CAC ÷ (ARPA × GM%).

The lifetime check uses the mean of a constant-churn model: average lifetime = 1 ÷ c, where c is monthly churn as a decimal, so 3% gives 33.33 months. Payback as a share of lifetime is payback ÷ lifetime × 100, which works out to payback × c × 100. First-year recovery is 12 × contribution ÷ CAC × 100, shown without a cap, so anything above 100% means the cost is repaid inside year one.

The verdict tests the lifetime first. If payback exceeds the average lifetime the result is never repaid, however short the payback looks; otherwise it is placed in a band: up to 6 months, up to 12, up to 18, up to 24, or beyond 24.

The model is deliberately simple. ARPA is flat, so expansion revenue from upgrades does not shorten the payback; churn is a constant rate, which flatters cohorts that lose most of their cancellations in the first few months; and no discount rate is applied to later months.

A worked example.

Frequently asked questions.

References& sources.

1. [1]Skok, D. "SaaS Metrics 2.0 — Detailed Definitions," forEntrepreneurs.com. Gives "Months to Recover CAC" as CAC ÷ (ARPA × GM%) with the historic guideline of less than 12 months. Undated revision, current as retrieved 2026-07-29.
2. [2]Skok, D. "SaaS Metrics 2.0 — A Guide to Measuring and Improving what Matters," forEntrepreneurs.com: "Many of the best SaaS businesses are able to recover their CAC in 5-7 months." Retrieved 2026-07-29.
3. [3]Bessemer Venture Partners — D'Onofrio, M. "Scaling to $100 Million" (updated 2024 edition, PDF). Source of the definition ("CAC payback is the rate at which the costs spent to acquire a customer are repaid by that customer, and it usually includes sales, marketing, and customer success expenses…"), the gross-margin adjustment, the 15-month average at $1–10M ARR, and the SMB/mid-market/enterprise targets of under 12, 18 and 24 months. Retrieved 2026-07-29.
4. [4]Bessemer Venture Partners — "The five accounting metrics for cloud companies," BVP Atlas. Defines CAC payback period as "the number of months required to pay back the upfront customer acquisition costs after accounting for the variable expenses to service that customer." Retrieved 2026-07-29.
5. [5]Gupta, S., Lehmann, D. R., & Stuart, J. A. (2004). "Valuing Customers." Journal of Marketing Research, 41(1), 7–18. Footnote 3 shows why a retention rate must not be treated as a fixed customer lifetime — the basis for this page's lifetime check rather than a fixed-term assumption. Author copy hosted by Columbia Business School; retrieved 2026-07-29.