The LTV:CAC ratio tells you how many euros of gross margin a customer returns over their lifetime for every euro you invested in acquiring them. You get it by dividing customer lifetime value (LTV) by customer acquisition cost (CAC). The target most often mentioned is 3:1, but that is a framework, not a law.
The ratio is useful because a low CPL or an attractive ROAS cannot distort it. It shows whether acquiring customers works in your favour financially once everything is added up.
How do we calculate LTV:CAC?
LTV:CAC = LTV ÷ CAC
You need two numbers:
- LTV (lifetime value) is the value a customer brings over their lifetime. The most useful version is LTV from gross margin: monthly revenue per customer × gross margin × number of months the customer stays.
- CAC is total marketing and sales cost divided by the number of new customers. The calculation is in the glossary entry What is CAC?.
What does the calculation look like in euros?
The example is made up and simplified. A company offers a service the customer pays for monthly.
| Figure | Value |
|---|---|
| Monthly revenue per customer | €500 |
| Gross margin | 50% |
| Average customer retention | 12 months |
| CAC (example from the CAC article) | €750 |
LTV from gross margin: €500 × 0.50 × 12 = €3,000
LTV:CAC = €3,000 ÷ €750 = 4:1
Every euro invested in acquisition returns €4 of margin. If you calculated LTV from revenue (€500 × 12 = €6,000), you would get 8:1. That is a nice number that does not reflect profit, so do not use it for decisions.
Add the payback time as well: the monthly margin per customer is €250 (€500 × 0.50), so a CAC of €750 is recovered in 3 months (€750 ÷ €250). The ratio tells you how much a customer returns. Payback time tells you how long you wait for that money, and that is often where cash flow gets stuck.
What is a good LTV:CAC ratio?
A commonly cited rule is a ratio of 3:1 or more. We do not cite a single verified public study for this figure, so treat it as a starting point for discussion, not a target that applies to every industry.
| Ratio | What it usually means |
|---|---|
| Below 1:1 | The customer does not even repay the cost of acquisition. Every new buyer makes the business worse off. |
| From 1:1 to about 3:1 | Acquisition pays off, but little is left over for other costs and mistakes. Check the payback time. |
| About 3:1 and above | The commonly cited target. Check that LTV really rests on margin and realistic retention. |
A very high ratio can be a sign of a healthy business, but sometimes also a sign that you are growing too slowly and could safely invest more. Payback time matters too: a 4:1 ratio with payback in 3 months is a different story from 4:1 with payback in 18 months.
What are the most common mistakes when calculating LTV:CAC?
- LTV from revenue instead of margin. The ratio is inflated.
- Retention that is too long or too optimistic. If you have data for 6 months, do not calculate with 36.
- CAC from ads only. Without sales and tools, CAC is too low and the ratio too high.
- One average for everyone. Customers from different channels or segments can have very different LTV and CAC. A separate calculation shows where to move the budget.
How do we use this ratio to manage advertising?
We measure the ratio once there is enough data, usually after 3–6 months of campaigns. At that point we move the ad budget to where the ratio is most favourable, not just to where CPL is lowest. Campaigns with a low CPL and low lead quality often push the ratio below 1. More on this in the article Why CPL is not enough and in the glossary entry What is CPL?.
For online stores we report on ROAS, CAC and LTV:CAC; how we do it is described on the performance marketing for online stores page. For enquiries for service and B2B companies, we connect the ratio with CRM data on closed deals: lead generation.
Sources: David Skok (For Entrepreneurs), SaaS Metrics: A Guide to Measuring and Improving What Matters (accessed October 2026) · HubSpot, What is a Good LTV to CAC Ratio? (accessed October 2026) · Andreessen Horowitz, 16 Startup Metrics (accessed October 2026) · David Skok (For Entrepreneurs), SaaS Metrics 2.0 (accessed October 2026)