The LTV:CAC ratio compares what a customer is expected to be worth over their lifetime with what it cost to acquire them. A ratio well above one means acquisition is creating value. A ratio near or below one means the company spends as much or more to win customers as it will ever earn from them. It is a common shorthand for whether growth spending is sustainable.
The formula
Both inputs need consistent definitions. LTV should be based on gross profit, not revenue, and CAC should include the same costs in every period you compare.
LTV:CAC = customer lifetime value ÷ customer acquisition cost
Example: $9,000 LTV ÷ $3,000 CAC = 3:1Why the ratio is fragile
LTV depends on a churn assumption, and for a young company with little history that assumption is a guess. A small change in expected churn can move LTV a lot. CAC depends on what costs you include and how you attribute customers to channels. The ratio inherits the uncertainty of both.
For that reason, many teams look at CAC payback period alongside it. Payback uses fewer assumptions about the distant future.
Using it by channel
A blended ratio hides differences between channels. Customers from organic search, paid ads, partners and outbound can have different acquisition costs and different retention. Calculating the ratio by channel, where the data supports it, shows which channels to expand. Keep sample sizes in mind: a channel with few customers will produce an unstable ratio.
Example
Two channels, two ratios
Hypothetical company Grisedale calculates an illustrative LTV:CAC of 4:1 for customers first acquired through organic search and 2:1 for a paid social campaign. Organic customers also retain longer in its data. The team shifts some budget toward content while flagging that the organic figure excludes content produced more than a year ago.
Common mistakes
Using revenue-based LTV
This overstates the ratio. Use gross profit per customer.
Treating a high ratio as always good
A very high ratio can mean the company is underinvesting in acquisition and growing more slowly than it could.
Questions
It is a widely repeated rule of thumb, not a law. The right ratio depends on margins, cash position, growth goals and how reliable your LTV estimate is.
