CAC payback period: formula, worked example and benchmarks

CAC payback period turns a sales and marketing budget into a number a founder can plan cash around: how many months until the customers it bought have paid it back. This page gives the formula, the steps, a worked example on a made-up company, the assumptions that change the answer, the benchmarks with their samples, and the way three companies define the metric in their SEC filings. It belongs to SaaS metrics. The rate at which customers leave, which the basic formula ignores, is covered in SaaS churn rate, and the recurring-revenue figures it divides by are explained in ARR vs MRR.

What the CAC payback period is

The CAC payback period is the number of months a company needs to recoup the initial costs of acquiring a new customer⁷. It is a SaaS metric that measures how long it takes to earn back spending on new customers, namely sales and marketing expense⁷. Customer acquisition cost, CAC, is the cost; payback is the clock. The clock only counts gross profit, because CAC payback looks at how much profit a customer will bring to the business, not total revenue¹⁰.

Bessemer, the venture firm whose benchmark report is used below, explains why the timing matters: only after CAC is repaid is the company generating profit on that customer, and during the payback period it is simply recovering the money spent to acquire the customer⁵. The result is a cash number as much as an efficiency number. CAC ties up working capital, and the longer the payback period, the longer the cash takes to come back⁶. Wall Street Prep puts a ceiling on it: the payback period determines the amount of cash a company needs to fund its growth strategies, so it sets a limit on what can reasonably be spent on acquiring customers⁷.

The CAC payback period formula

Three inputs are needed: sales and marketing expense, new MRR and gross margin¹⁰. The most-quoted form divides the expense by the margin-adjusted new revenue⁷.

Published recipes differ in what they put in each input. This table lines up the ones used below.

Wall Street Prep adds a warning that there are numerous other ways to calculate CAC payback, so the pros and cons of each need to be understood⁷. One example: the net new MRR metric, which is new MRR adjusted for expansion MRR and churned MRR, could be used as the recurring-revenue component⁷.

How to calculate CAC payback period

1. Total the acquisition spend. Take fully loaded sales and marketing costs from the P&L, and allocate the spend between new and existing customers⁶. The spend usually includes marketing, sales staff and other direct acquisition costs⁸.
2. Count the new customers and their new MRR. CAC is the spend divided by the customers acquired in the same period⁹. New MRR is the recurring revenue those customers brought in¹⁰.
3. Apply gross margin. Use the margin on subscription revenue, since the variable costs of delivering the product do not accrete to profit⁵.
4. Divide. Divide the CAC by the monthly gross profit per customer, or the whole spend by the whole cohort's monthly gross profit. The result is months^{8, 7}.

An example calculation: Larkspur’s quarter

Worked example (our arithmetic): Larkspur, one quarter (formula from⁷, per-customer form from⁸)

Larkspur is a made-up software company. All inputs are invented round numbers.

The cohort check is exact: $450,000 ÷ $48,000 = 9.375 months. The per-customer line uses rounded dollars and lands on the same answer.

The same company under three recipes

The answer changes with the recipe, not with the company.

Worked example (our arithmetic): Larkspur under three recipes (recipes from⁷ and¹)

The Klaviyo-style figure is longest because it divides the trailing year’s spend by the change in total revenue¹. That change nets out expansion and any customers lost, so churn shows up in it where the first recipe leaves it out. None of the three is wrong. They answer different questions, which is why a payback figure without its recipe cannot be compared.

Important assumptions behind the number

Each input hides a choice. Write the choice down next to the number.

• Which revenue counts as new. Corporate Finance Institute counts the new and expansion revenue associated with new and existing customers⁸. Others note that some companies use net new MRR to account for churn, and that expansion MRR from existing customers can be included or excluded¹⁰. If existing customers are in the calculation, adjust the formula to include expansion MRR¹⁰.
• Which spend counts. Sales and marketing expense covers sales teams, digital marketing, ad spending, search engine marketing and related tactics⁷. Bessemer’s version also includes customer success expenses, at least the portion tied to renewal, upsell and cross-sell⁵. ServiceTitan adds the costs of implementation services to complete onboarding².
• Which margin applies. SaaS gross margin is revenue less cost of goods sold, and the largest costs are usually hosting and onboarding⁷. Klaviyo and ServiceTitan both use an adjusted gross profit figure, and Klaviyo’s recipe also takes out stock-based compensation^{1, 2}.
• Which period. A monthly, quarterly or trailing twelve-month window changes the noise in the figure. Klaviyo uses twelve months on each side¹, ServiceTitan trailing four quarters².
• Which revenue unit. With ARR in the formula, multiply by 12 to put the result in months, and with MRR drop the multiplication⁶.

Time value of money and churn

The basic formula leaves two things out. It does not factor in churn or the time value of money⁶. Churn matters because paying back CAC works like repaying debt out of a stream of income: if a customer leaves, the remaining payments still have to be made, and the next customers have to cover the acquisition cost of those who left⁶. Wall Street Prep reaches the same point from the risk side: the longer recovery takes, the greater the risk of losing the upfront investment, because of weak retention and lost profits⁷. The Larkspur table shows the size of the effect: 2% of revenue leaving each month adds about a month to a payback of just over nine (our arithmetic from that table).

The time value of money is the second gap. The formula does not account for the fact that CAC is paid off over time, and a dollar in the future is worth less than a dollar today⁶. With long payback periods the opportunity cost of the tied-up money grows, which makes the practical payback longer than the simple one⁶. If your own growth requires borrowing or raising to fund acquisition, that is the cost to weigh against the simple number. The churn page has the monthly-to-annual conversion needed to put a monthly leaving rate into this kind of check.

What is a good CAC payback period?

There is no single answer, and the sources that give one say so. A strong target is generally less than 12 months, and the ideal can vary significantly with the business model and market dynamics⁸. A high-touch SaaS business with substantial lifetime value might tolerate a longer period, since the return on each acquisition is greater over time⁸. The payback figure also has to be evaluated with customer types, revenue concentration, billing cycles and working capital needs before it can be called good or bad⁷.

Size and segment change the target. Small companies sometimes must have a shorter payback because they have less access to cash than larger ones¹⁰. Early-stage businesses can have longer payback periods because they invest heavily to build an initial customer base and find product-market fit⁹. B2B businesses often have longer sales cycles and higher CACs than B2C⁹, and selling to enterprise customers usually brings higher annual contract values but also longer sales cycles⁹.

CAC payback period benchmarks

Read the sample before the number. These are the benchmarks used by finance teams, with their source and what they cover.

Bessemer’s sample is its own cloud portfolio: it has made over 200 cloud investments and runs one of the largest cloud portfolios of any venture firm⁵. It explains why its segment targets differ: SMB, mid-market and enterprise buckets tend to have different annual contract values and churn rates, so enterprise-focused companies can support longer payback periods⁵. Shorter is always better within any segment, since customers only become profitable after payback⁵.

The editors’ reading: the “12 months” figure repeats across four secondary sources without a stated sample^{7, 8, 9, 10}, while the only segmented benchmark comes from Bessemer’s portfolio⁵. The filings are a useful reality check. Klaviyo’s 14 months and ServiceTitan’s 21 months sit on either side of the headline rule, and each reflects its own recipe^{1, 2}. Benchmark against companies that sell at your price point: The SaaS CFO warns that aggregate SaaS benchmarks are dangerous, and says to benchmark by firmographics⁶.

How public companies define CAC payback

The SEC’s guidance on key performance indicators asks a company to give a clear definition of the metric and how it is calculated, and a statement of why it gives useful information to investors⁴. It also asks whether prior metrics should be recast when the method changes⁴. Both Klaviyo and ServiceTitan label the gross profit in their formulas non-GAAP^{1, 2}, a category the Commission keeps apart from operating statistics such as numbers of subscribers, which it has said are not non-GAAP financial measures⁴. Three registration statements show what that looks like for payback.

Klaviyo’s amended S-1 defines CAC payback as the number of months it would take for gross profit, adjusted for stock-based compensation, to exceed adjusted selling and marketing expenses¹. The calculation starts from the change in revenue over the twelve months to the date of determination, multiplies it by the gross margin of those twelve months excluding stock-based compensation, and divides by selling and marketing expense for the same period, adjusted for stock-based compensation and the amortization of a prepaid marketing expense tied to the Shopify Warrants¹. The company takes the quotient of 12 and the result¹. It reported 14 months for the quarter ended June 30, 2023¹.

ServiceTitan’s amended S-1 divides customer acquisition costs for the trailing four quarters by the platform gross margin for those quarters minus the platform gross profit for the prior four quarters, then multiplies by 12 to give months². Its customer acquisition costs include up-front sales and marketing costs and the costs of implementation services to complete onboarding². It reported approximately 21 months as of July 31, 2024².

Xometry’s amended S-1 uses a simpler description for its U.S. marketplace: the average number of months required to fully recoup CAC in the reporting period³. It reported 2.1 months for 2020 and 3.5 months for 2019, next to an LTV/CAC ratio that shows the average LTV buyers are expected to generate as a multiple of CAC³. A marketplace with fast repeat orders and a subscription business with annual contracts will not sit on the same scale.

CAC payback vs LTV:CAC

The two ratios answer different questions. The payback period shows how soon the money comes back, and the LTV:CAC ratio shows how much comes back in total. Stripe’s framing: the ratio is primarily concerned with long-term profitability and the return on acquisition efforts, and a generally accepted benchmark for a healthy ratio is 3:1 or higher, meaning lifetime value is at least three times the cost of acquisition⁹. Bessemer reaches a similar threshold: it recommends investing in customer acquisition when CLTV over CAC is 3x or more, and experimenting further when it is much lower⁵. Look at both. A long payback with a very high lifetime value can still work, and a short payback with a low ratio can hide a leaky customer base^{8, 7}.

How to improve CAC payback period

Payback is a ratio, so it improves by cutting the numerator, raising new gross profit, or both. Treat the list as hypotheses to test against your own cohorts.

• Fix the funnel. Look at each type of marketing, such as pay-per-click ads, email and social ads, and see which are most effective¹⁰. Segmentation helps by identifying high-value customer profiles with shorter sales cycles and higher lifetime value⁹.
• Shorten time to value. Self-service onboarding, interactive tutorials and proactive support reduce friction and speed up time to value for new customers⁹.
• Line up sales and marketing. Consistent messaging, efficient lead handoff and shared accountability for revenue goals keep acquisition spend from leaking between teams⁹.
• Sell more to existing customers. Upselling to higher-tier plans or cross-selling complementary products makes each dollar go further, but the formula has to be adjusted to include expansion MRR^{9, 10}.
• Review price and margin. A higher gross margin shortens payback, and the margin can be raised by cutting expenses, although fixed costs such as hosting and payroll are hard to reduce¹⁰.
• Watch the cash side. Some direct-to-consumer startups that rely on paid channels have aimed to be net profitable on a customer’s first transaction, which makes payback close to zero¹⁰.

Common mistakes

The cash consequence of a long payback is the subject of burn rate and runway: every month of payback is a month of cash tied up.

• Using revenue instead of gross profit. Payback measures how much profit the customer brings, not total revenue¹⁰.
• Mixing recipes across reports. A Klaviyo-style figure and a new-MRR figure for the same company can differ by months, as the Larkspur table shows.
• Counting the whole customer base’s ARPA. The cohort input is the average ACV landed from new customers, not the ARPA of the entire base⁶.
• Skipping the allocation. Sales and marketing spend must be split between new and existing customers⁶.
• Reading payback as a profit measure. After payback, customers start to be profitable; before it, the company is only recovering what it spent⁵.
• Ignoring churn and the cost of waiting. The simple formula does not factor either in⁶.
• Quoting a benchmark without its sample. Bessemer’s targets differ by segment for reasons it states⁵.