Why it matters
If customers come back, the first order isn't the whole story. A brand that only accepts a CPA below first-order margin may under-invest and cede ground to rivals who know their repeat rate. LTV lets you set a first-order CPA above first-order break-even — on purpose — because you know what later orders are worth.
How to calculate it
Use contribution margin, not revenue, and a fixed time window.
- Take a group (cohort) of customers who first bought in the same month.
- Count all their orders over the next 12 months (or 3, or 6).
- Divide by the number of customers to get orders per customer.
- Multiply by your contribution margin per order.
Measure this from your own store data. If you're new and have no history, be conservative: assume little or no repeat business until your cohorts prove otherwise.
Worked example
Example: 1,000 customers acquired in January, with ₹450 contribution margin per order.
| Window | Orders | Orders per customer | Margin per customer |
|---|---|---|---|
| First order | 1,000 | 1.0 | ₹450 |
| 90 days | 1,200 | 1.2 | ₹540 |
| 12 months | 1,600 | 1.6 | ₹720 |
If ads must pay back within 90 days, your maximum first-order CPA is ₹540. If you can wait a year, it's ₹720 — even though the first order alone only covers ₹450.
Payback period
Payback period is how long it takes a customer's cumulative margin to cover what you paid to acquire them. Shorter payback means cash returns sooner to fund more ads. Pick a payback window your cash flow can survive, then set target CPA from the LTV for that window, not the lifetime figure.
How to use it
- Set CPA targets per product: a consumable people reorder can carry a higher CPA than a one-off purchase.
- Check your targets with the CPA calculator, using the margin you can afford per customer.
- Use custom audiences of past buyers for reorder campaigns — and count that spend when you calculate LTV.
- Watch blended results through MER, since repeat revenue shows up in your store but not always in Meta.
Spending ahead of LTV borrows against future orders. If repeat rates slip, the profit you counted on never arrives, so re-check your cohorts every month.
Common mistakes
- Using revenue LTV instead of margin LTV.
- Assuming a five-year "lifetime" for a brand that's two years old.
- Ignoring the cost of the email, WhatsApp and retargeting that drive repeat orders.
- Applying one LTV to every product and acquisition channel.
Frequently asked questions
How do you calculate customer lifetime value for an online store?
Group customers by the month they first bought, count their orders over a fixed window such as 12 months, and divide by the number of customers. Multiply those orders per customer by your contribution margin per order. Using margin rather than revenue tells you what you can actually afford to spend to win a customer.
Should I use LTV to set my Facebook ads CPA?
Yes, if you have enough repeat-purchase data to trust it. Base your first-order CPA on the margin customers generate within a payback window your cash flow can handle, such as 90 days, rather than their full lifetime. New brands without that data should stick to first-order margin until their cohorts prove repeat rates.
What is the payback period in e-commerce?
It's how long it takes a customer's cumulative margin to cover what you spent to acquire them. If you pay ₹600 to win a customer who brings ₹450 of margin on the first order and another ₹450 three months later, payback takes about three months. Shorter payback frees up cash for more advertising sooner.
