Practical guide

LTV:CAC ratio formula and what a 3-to-1 result means

Calculate LTV:CAC on a consistent margin basis and see why a ratio is not a guarantee of profitable growth.

Updated 2026-09-06 · Sources checked 2026-09-06

What is the LTV:CAC ratio?

The ratio divides estimated customer lifetime value by customer acquisition cost. If modeled LTV is $3,000 and CAC is $1,000, the result is 3, commonly written 3:1. It describes the relationship between two inputs; it does not validate either input.

Keep the numerator consistent

Consider an illustrative customer paying $100 monthly with 80% gross margin and 4% monthly customer churn. The margin-adjusted steady-state LTV is $100 × 0.80 ÷ 0.04 = $2,000. With $800 CAC, the ratio is 2.5:1.

Using revenue-only LTV of $2,500 would produce 3.125:1 instead. Nothing about customer behavior changed; only the treatment of service costs changed. Record whether LTV represents revenue, gross profit, or another contribution measure before comparing ratios.

Enter $2,000 and $800 in this calculator. Calculate LTV and CAC separately first, then keep their assumptions with the ratio. The tool does not infer churn or acquisition costs from the final figures.

Test the fragile assumption

If monthly churn in the example increases to 5%, margin-adjusted LTV becomes $1,600 and the ratio falls to 2:1. If CAC also rises to $1,000, it falls further to 1.6:1. Those scenarios show how a plausible input range can matter more than another decimal place in the output.

Ratio questions

Is 3:1 always good?

The calculator does not apply a universal benchmark. Cash recovery time, uncertainty in retention, overhead, growth requirements, and customer concentration can change how a business interprets the same ratio.

What if CAC is zero?

The tool returns zero when the denominator is zero. That display is not a meaningful zero ratio. Check whether acquisition spending was omitted, whether the customer group was acquired in another period, or whether a ratio is simply undefined for the chosen inputs.

Use the ltv cac ratio calculator to reproduce the scenario with your own inputs.