Why it matters
The ratio answers one question: for each dollar spent winning a customer, how many dollars of gross margin come back over their life? Above one, growth creates value. Below one, every customer costs more than they return.
It is useful because it joins the two sides of growth in one number. A business with a low CAC can still be weak if customers leave quickly, and a business with a high CAC can be strong if customers stay and expand. The ratio shows which side is carrying the result.
The formula
Work out customer lifetime value from monthly margin and churn. Work out customer acquisition cost from sales and marketing spend and new paying customers. Divide the first by the second. The result is the margin returned per dollar spent on acquisition. Use margin in the lifetime value, not revenue, and use fully loaded acquisition cost.
LTV to CAC = LTV / CAC
LTV = ARPA x gross margin / monthly churnA worked example
The lifetime value and acquisition cost from the earlier examples are compared here. These numbers are made up for illustration.
| Example numbers | Value |
|---|---|
| Customer lifetime value | $3,000 |
| Customer acquisition cost | $700 |
| LTV to CAC ratio | 4.3 to 1 |
| Lifetime value if monthly churn doubles | $1,500 |
| Ratio if monthly churn doubles | 2.1 to 1 |
A lifetime value of $3,000 against an acquisition cost of $700 gives a ratio of 4.3 to 1. The second block shows how fragile it is: doubling monthly churn halves the lifetime and halves the ratio to 2.1 to 1, with no change in what customers cost to win.
How to improve it
The ratio improves when value per customer rises or acquisition cost falls, and the two are worked on separately.
- Reduce churn, which lengthens lifetime and lifts value for every customer, old and new.
- Raise ARPA and margin with pricing and packaging, so each month of a customer's life returns more.
- Lower CAC with better conversion and cheaper channels, without lowering the quality of customers.
- Check the ratio by channel and plan, and move spend toward the segments with the strongest ratio.
Common mistakes
- Building the lifetime value from revenue instead of gross margin, which inflates the ratio.
- Using only part of acquisition cost, such as ad spend, so that the denominator is too small.
- Quoting the ratio without payback. A strong ratio with a long payback can still starve a business of cash.
- Using a churn rate from a few good months to produce a long lifetime, then comparing it with today's cost to win a customer.
- Pursuing a higher ratio by cutting acquisition spend, which can shrink growth while the figure looks better.
Calculate it and read next
Work it out with your own figures in the customer lifetime value calculator. Then read about Customer lifetime value, Customer acquisition cost and CAC payback period.
- Customer lifetime value: the numerator, built from margin and churn.
- Customer acquisition cost: the denominator, built from spend and new customers.
- CAC payback period: the cash view of the same comparison.
Frequently asked questions
Is a higher LTV to CAC ratio always better?
Not always. A very high ratio can mean you are under investing in growth. The useful question is whether more acquisition spend would still return more than it costs.
Should the ratio use margin or revenue?
Margin. Revenue ignores the cost of delivering the product and inflates the ratio.
How does the ratio relate to payback?
Both compare value with cost. The ratio looks at total value over the lifetime and payback looks at how quickly the cost is recovered, so you need both.
What if I have too little history to measure churn?
Use your best available churn estimate, show the ratio at a range of churn values, and update it as customers age. Treat it as a guide until you have a longer record.