Customer Lifetime Value (LTV) to Customer Acquisition Cost (CAC) ratio for a Shopify store
By the HonestTag team · Published November 10, 2026 · Updated November 11, 2026
The 3:1 rule was written for software companies, worked on revenue, with gross margins of 80% or more. Here is how to work the ratio out for a store, over which months, and how to read it beside the month a customer pays back.
Work the ratio out on margin, over fixed windows such as a customer's first 3, 6 and 12 months, and read it next to the payback month. The 3:1 target comes from software guidance that uses revenue and assumes a gross margin of 80% or higher. On a store's revenue, the same ratio can look healthy while the margin a customer has brought in has not yet covered what they cost. Shopify's own guide calls 3:1 a common reference point that does not fit every business.
Revenue LTV or margin LTV
The ratio divides what a customer brings in by what it cost to win them. The choice that moves it most is what "brings in" means. Revenue counts the money you pay your suppliers as if you kept it. Shopify's margin-adjusted formula multiplies by gross margin, and investors at Andreessen Horowitz warn that a revenue or gross margin LTV "suggests a higher upper limit on what you can spend on customer acquisition."
Gross margin is the practical floor: revenue times the share left after the cost of the goods. Andreessen Horowitz goes a step further and prefers contribution margin, which also takes off the selling and operating costs of serving each customer. If you know those costs, use them. Either way, the number you compare with acquisition cost should be money you kept.
Fixed windows instead of "lifetime"
The textbook lifetime value formula estimates a customer's lifespan from a churn rate: one divided by the share of customers who cancel each month. That works for a subscription, where a cancellation is an event you can count. A store customer who is not on a subscription rarely cancels anything. They just stop ordering, so "lifetime" turns into a guess about the future.
Andreessen Horowitz's advice for a business with little history is to measure value to date instead: "we prefer to measure 12 month and 24 month LTV." For a store, fixed windows answer separate questions. The first 3 months (about 90 days) shows whether the first order and early repeats cover the cost. The first 6 and 12 months show whether repeat buying makes a customer worth more than their first basket. Count only customers who have had the whole window: a customer acquired last month has not had 6 months to come back.
Why 3:1 is a software number
The 3:1 guideline comes from David Skok's SaaS Metrics, written for software-as-a-service (SaaS) companies: "Our guideline for a successful SaaS business is that this number should be higher than 3." His definitions page says what it assumes: the simpler LTV formula with no gross margin adjustment, and "a Gross Margin of 80% or higher." He adds that most SaaS businesses have gross margins above 80%, which is why revenue worked as a shortcut there.
A store's margin is its own, and the shortcut only holds if yours is that high. The numbers below are made up to show the arithmetic. A customer brings in $200 of revenue in their first 12 months and cost $50 to acquire:
- On revenue: $200 against $50 is 4:1, which clears 3:1 easily.
- At a 40% gross margin: the customer brought in $80 of margin, so the ratio is 1.6:1.
- At the 80% margin Skok's guideline assumes: $160 of margin, 3.2:1.
Read the other way, 3:1 on revenue at an 80% margin is 2.4:1 on margin. That is the bar the guideline describes once margin is counted, and it was set for subscription software, not for a store. Skok himself calls these "only guidelines." Shopify's guide says the target "depends on your margins and operating costs" and to compare LTV with "your margins, payback period, cash needs, and historical results."
Read lifetime value on margin, beside payback. On higher plans, Cohorts shows each customer group's payback month and, on gross margin only, your store's lifetime value against New-Customer Acquisition Cost (NCAC) at 3, 6 and 12 months.
Read the ratio with the payback month
Skok paired 3:1 with a second guideline, months to recover the acquisition cost, and wrote that SaaS profitability "is anemic if the time to recover CAC extends beyond 12 months." His definitions page later relaxed that bar for software companies that can raise money easily: "it is quite common to see very healthy SaaS businesses taking around 20 months to recover CAC." The ratio says how much a customer is worth against their cost. The payback month says how long your cash is out before it comes back. A store that pays back in 2 months can fund the next customers from the last ones. A store that pays back in 11 months needs the cash to wait.
The same made-up customer, 40% gross margin, $50 to acquire, counting the month of the first order as month 0: by the end of month 2 they have brought in $90 of revenue, by the end of month 4 $120, by month 5 $130 and by month 11 $200. On margin that is $36, $48, $52 and $80. So the ratio is 0.72:1 over the first 3 months, 1.04:1 over the first 6 and 1.6:1 over the first 12, and the margin first passes $50 in month 5. For one group of customers, a window's ratio reaches 1:1 in the window that holds the payback month. Two stores can both show 1.6:1 at 12 months while one paid back in month 2 and the other in month 11.
Check what the cost in the ratio counts. A blended cost divides all ad spend by all new customers, including the ones who would have found you without an ad, so it reads lower than the cost of the customers your ads bought. Bill Gurley names that shortcut among the ways the LTV formula gets misused. Blended CAC vs paid CAC covers the difference.
What this means
The ratio is the margin a group of customers has brought in for each dollar it cost to win them, over a window they have all lived through. Below 1:1, that group has not yet paid back its cost, and the window in which it crosses 1:1 holds the payback month: how long your cash is out. A ratio that climbs from the 3-month to the 12-month window means repeat buying is doing the work. One that barely moves means customers are worth about their first basket, so the first order has to carry the cost.
Compare groups at the same age. A ratio that slips from one group to the next says new customers are costing more to win or bringing in less, which one figure held against 3:1 hides. Worked out on revenue, the ratio flatters the store and makes room for spend its margin cannot pay for. On higher plans, HonestTag puts the ratio on gross margin and the payback month on one screen, counted from your Shopify orders.
How HonestTag helps
HonestTag counts new customers from your Shopify orders and puts the ratio and the payback month on one screen.
- On the free Mirror plan, The Gap shows how many of your new customers first arrived from a Google Ads or Meta click, counted from your store's real orders over the 14 days up to yesterday.
- On higher plans, Cohorts groups customers by the month of their first order, tracks revenue per customer month by month, and marks the payback month against your store-wide blended NCAC over the last 90 days.
- The LTV to NCAC ratio for the first 3, 6 and 12 months sits beside it, and on the Scorecard once there is a ratio to show. It is worked out on gross margin only. Where no gross margin is on file for the store, Cohorts says so in place of a ratio rather than show one on revenue.
- Only customer groups that have completed a window count toward it, and a window none has completed shows no number, with the reason.
- One projected 12-month figure appears for younger customer groups when at least 3 older groups of 30 or more customers each have completed 12 months. It carries a ~, and a confidence badge where those older groups are few or disagree, and is never added to the measured figure.
The ratio is store-wide only, like payback: a ratio per ad channel would need spend split the same way as customers.
Install HonestTag free from the Shopify App Store and see on the Mirror plan how many new customers your Google Ads and Meta clicks brought, counted from your orders.
Frequently asked questions
What is a good LTV to CAC ratio for a Shopify store?
There is no one number. The usual 3:1 comes from software guidance that uses revenue and assumes a gross margin of 80% or higher, and Shopify calls it a common reference point that does not fit every business. Work the ratio out on your own margin, then judge it with your payback month and your cash.
Should LTV be calculated on revenue or profit?
On margin. Revenue counts what you pay suppliers as if you kept it, so it overstates what you can afford to spend on a customer. Gross margin is the practical floor; contribution margin, which also takes off the costs of serving each customer, is stricter.
What is the difference between LTV to CAC and CAC payback?
The ratio says how much margin a customer brings in against what they cost. Payback says in which month that margin first covers the cost. Two stores can share a 12-month ratio and pay back in very different months, which changes how much cash each needs.
Why measure LTV over 90 days or 12 months instead of a lifetime?
A lifetime figure needs a guess about how long customers keep buying, and store customers who are not on a subscription rarely cancel anything you can count. A fixed window uses only what customers have already spent, and counts only customers who have had the whole window.
Does HonestTag show the ratio for each ad channel?
No. The ratio and the payback month are store-wide, using blended NCAC. A ratio per channel would need ad spend split by the same rule as the customers.
Sources
- David Skok, For Entrepreneurs: SaaS Metrics 2.0, A Guide to Measuring and Improving what Matters, read November 10, 2026
- David Skok, For Entrepreneurs: SaaS Metrics 2.0, Detailed Definitions, read November 10, 2026
- Andreessen Horowitz: 16 Startup Metrics, read November 10, 2026
- Shopify blog: Customer Lifetime Value, How To Calculate CLV, read November 10, 2026
- Bill Gurley, Above the Crowd: The Dangerous Seduction of the Lifetime Value (LTV) Formula, read November 10, 2026
- Shopify Community: What to measure in your first 90 days (merchant thread, October 24, 2025), read November 10, 2026
- HonestTag: Cohort payback
- HonestTag pricing and plan limits
Related reading: cohort payback, Customer Lifetime Value (LTV) projection, New-Customer Acquisition Cost (NCAC), and blended CAC vs paid CAC.
Read lifetime value on margin, beside payback
On higher plans, Cohorts shows each customer group's payback month and, on gross margin only, your store's lifetime value against New-Customer Acquisition Cost (NCAC) at 3, 6 and 12 months.
- Feed your ads a clean signal. On paid plans, the platforms you send to get each verified purchase, new customers marked as new once confirmed.
- Catch the sales your pixels miss. On paid plans, purchases are sent from your Shopify orders, server to server.
- Know what to scale. From the Truth plan, a weekly scale, hold or cut call when the data supports one, and on every paid plan, proof behind every attributed order.
- Start free. The free Mirror plan puts Google Ads and Meta claims beside your orders. Keep your current tracking while you look.