What is LTV/CAC Ratio?
Short answer: The LTV/CAC ratio compares expected lifetime contribution from a customer with the cost of acquiring that customer. It is a unit-economics indicator, not a measure of total profit, cash generation or the speed at which acquisition spending is recovered.
The numerator and denominator must use the same customer definition, channel, geography and cohort. Contribution-based LTV should be compared with a clearly scoped CAC. Dividing lifetime revenue by a fully loaded cost mixes economic bases and inflates the result. A ratio can look strong while the business destroys cash because benefits arrive slowly, fixed costs are high or the addressable market is small. It can also look unusually high when a company underinvests in growth. Payback period, cohort maturity, retention and total contribution provide essential context.
How it works
Calculate LTV and CAC separately with version-controlled definitions. Match cohorts and allow for acquisition-to-conversion lag. Reconcile cost and revenue inputs to management accounts, then segment the ratio by channel and customer type. Track both forecast LTV/CAC at acquisition and realised performance as cohorts mature. Bridge changes to acquisition cost, pricing, margin, churn and expansion rather than reporting a new ratio without explanation. Test sensitivity to retention because long implied lifetimes amplify small errors. For capital planning, combine the ratio with monthly acquisition volume and payback to determine the cash required before contribution is recovered.
LTV/CAC ratio = customer lifetime value / customer acquisition cost
Example
A customer cohort has contribution-based LTV of 2,400 and fully loaded CAC of 800, so LTV/CAC is 2,400 / 800 = 3.0x. Monthly contribution per retained customer is 80, giving a simple CAC payback of ten months before allowing for churn. If revised cohort evidence reduces LTV to 1,600 while CAC remains 800, the ratio falls to 2.0x. Acquiring 1,000 customers at the original CAC still requires 800,000 of upfront spending, which the ratio alone does not show.
Why it matters
Founders and CFOs use the ratio to compare acquisition channels and set spending guardrails. Boards assess whether growth targets rely on uncertain customer lifetimes. Lenders focus on the associated burn, payback and contracted revenue rather than the ratio alone. Buyers test definitions and reconstruct cohorts before including the economics in valuation. Sellers use consistent historical vintages to support scalability. Equity investors combine LTV/CAC with market size, retention and marginal CAC to judge the value of incremental growth.
There is no universal acceptable ratio. Business model, capital cost, payback, gross margin and growth stage change the interpretation. Immature cohorts, survival bias, omitted service costs and blended organic acquisition can overstate performance. A ratio based on forecasts is not an accounting-standard measure or assurance of future results. Public disclosure should define the components and explain material changes, while transaction diligence should test the underlying customer and spend records.