The LTV/CAC ratio divides customer lifetime value by customer acquisition cost, measuring whether a company earns enough from a customer to justify what it spends to win them. A ratio near 3:1 is a common SaaS health benchmark; much higher can signal underinvestment in growth.
The metric only makes sense alongside CAC payback period, since a strong ratio with very slow payback can still strain cash.
Reading the ratio — and its limits
The LTV/CAC ratio compares the lifetime value of a customer to the cost of acquiring one, and it is the quickest read on whether a business model works. A widely cited benchmark is roughly 3:1 — below 1:1 you lose money on every customer; far above 3:1 you may be under-investing in growth. But the ratio is only as honest as its inputs: LTV that assumes optimistic retention or ignores cost-to-serve, or CAC that excludes salaries and overhead, produces a flattering but misleading number. It should be read with the CAC payback period and gross margin, and recalculated by channel and cohort, because a healthy blended ratio can hide an unprofitable acquisition channel underneath.
Reading the ratio honestly
The market shorthand is 3:1, but the ratio is only as good as its ingredients: LTV should be computed on gross margin (not revenue), churn assumptions should come from cohort data rather than aspiration, and CAC should be fully loaded including sales and marketing salaries. A very high ratio is not automatically good news — 6:1 and above often signals under-investment in growth. Read it together with CAC payback: a strong ratio with a 24-month payback still consumes capital. In transactions these metrics become representations — investor decks’ LTV/CAC claims get recomputed from raw data in diligence, so writing the definitions (which margin, which churn, which costs) into the data room closes the surprise category.