LTV:CAC ratio
The LTV:CAC ratio is the value a customer brings a store across all their orders, divided by what it cost to win that customer.
How it works
The ratio compares customer lifetime value, what a customer brings over all their orders, with customer acquisition cost, what the store spent to win them. Counted on gross profit, a ratio above 1 means a customer brings back more than they cost; below 1, each new customer is a loss.
Google Ads shows neither number: repeat orders are recorded in the store’s own order history, so the store counts the ratio from its own data. There is no single benchmark for online stores: the level a store needs depends on margin, order costs and how long it can wait for repeat orders. How much a first order can afford to lose: LTV:CAC for online stores.
Formula
Customer lifetime value ÷ customer acquisition cost
Ways to calculate
- On revenue. Lifetime value = average order value × orders per year × years as a customer (Shopify, What Is Customer Lifetime Value?).
- On gross profit. The same value × gross margin, which shows profit per customer (Shopify, Customer Acquisition Cost (CAC)).
Example
Example store, not client data.
The tableware shop spends 40,000 a month; 180 of its 300 orders are first purchases. If all spend is charged to new customers, CAC = 40,000 ÷ 180 ≈ 222.
On average, a customer places 1.6 orders of 600 over two years: LTV is 960 in revenue, or 336 in gross profit at a 35% margin. LTV:CAC = 960 ÷ 222 ≈ 4.3 on revenue, 336 ÷ 222 ≈ 1.5 on gross profit. The first order leaves 210 of gross profit against 222 of CAC, so the shop is 12 behind until a second order.
Right and wrong readings
- Wrong: “3:1 is the norm for online stores.” Right: it is David Skok’s guideline for SaaS start-ups, restated in 2013: LTV above 3× CAC. In the example, the same customers give 4.3 on revenue and 1.5 on gross profit, so first ask which LTV a ratio uses.
- Wrong: “An order that costs more in ads than it earns is always a loss.” Right: in the example, the first order is 12 behind, but 336 of lifetime gross profit covers 222 of CAC, provided the store’s order history confirms the 1.6 orders.
Sources
- SaaS Metrics 2.0 – A Guide to Measuring and Improving what Matters — the “LTV > 3x CAC” guideline for SaaS start-ups, restated in 2013. Checked 2 October 2026.
- Customer Acquisition Cost (CAC): Calculate and Reduce It — CLV to CAC, the gross margin step. Checked 2 October 2026.
- What Is Customer Lifetime Value? How to Calculate CLV — the CLV formula. Checked 2 October 2026.