The 3-to-1 figure is everywhere, but it comes from a different business: David Skok popularized it for subscription software companies, whose customers pay every month for years.
Keep it as a starting point. For an e-commerce brand, the useful question is more down to earth: how many months does it take a customer to pay back their acquisition cost, calculated on margin?
The benchmark
Two calculations are enough. Twelve-month customer value adds up the contribution margin generated by each acquired customer, before acquisition cost. Payback period counts the months it takes for that margin to cover that cost. The second speaks to your cash flow, the first to your strategy.
Skok sets the limit at twelve months for software companies, and notes that the best ones pay back in five to seven. In e-commerce, where nothing forces anyone to come back, we read that limit as a ceiling.
A rough order of magnitude helps set expectations. At one fashion brand the authors work with, customer value, measured in revenue in this first calculation, grows 35 to 40% between a customer's first order and their twelfth month.
So the first order carries most of the year's value, and repeat purchases add a good third on top. If your plan assumes value that doubles in a year, find out where that assumption comes from.
The rule
Calculate by cohort and by channel. A blended ratio mixes loyal customers who came through word of mouth with one-time buyers who came through ads, and the average describes no one.
The same brand saw it by slicing by acquisition month: a year later, cohorts acquired at full price were worth more than those acquired during the sales.
The steps
- Cohorts. Group your new customers by acquisition month and by channel. A Shopify order export is enough to get started.
- Margin. Add up each cohort's contribution margin over twelve months.
- Fully loaded cost. Divide by the channel's acquisition cost, including everything acquisition costs you: ads, commissions, tools, agency fees, and the share of salaries devoted to it.
- Sorting. Spot the channels that don't pay back within a year.
- The line for leadership:
"This channel pays back in X months, fully loaded. Under a year, we can speed up. Beyond that, we need a reason other than sales to keep it."
The trap
The most common one is calculating customer value in revenue. A customer who spent €300 didn't earn you €300. We're not immune either: the first spreadsheet built with the brand mentioned above was in revenue, because that's what the export gives you.
The second trap looks better, and that's what makes it dangerous. On that same spreadsheet, some ratios climbed as high as 10 to 1. Nobody popped the champagne. A ratio that high first signals an incomplete acquisition cost, one that doesn't yet include the team's salaries or agency fees.
The ratio only measures what you've agreed to put in the denominator, so fully load the cost before celebrating an 8 or a 10.
Finally, beware of yesterday's loyalty. Your customers from three years ago often found you without advertising, and nothing says the ones you buy today will come back at the same pace.
Your site, meanwhile, affects all three terms of the calculation. Conversion lowers acquisition cost, first-order basket size shortens payback, and repeat purchases extend value.
When the first order weighs as much as it does in our example, basket size is where we'd start.
