When it pays to stop buying new customers
Retention gets recommended as an article of faith, but the decision can be calculated. A simple sum that shows where the next koruna belongs.
“Keeping a customer is cheaper than winning a new one” is true often enough that people stopped checking. Yet it is a decision about where the next koruna goes — and that can be calculated rather than assumed.
What you need to know
Three numbers from the last twelve months are enough: what an order from paid channels costs, what share of customers buy a second time, and how much returning customers spend compared with first-time ones.
Most shops know the first precisely, the second roughly, and the third not at all. The third is the one that decides.
A simple test
Work out what you earn from a customer over the year following their first purchase. Compare it with what that customer cost to acquire. If the ratio is tight, acquisition only appears to be feeding you — you grow in volume and stand still in profit.
Then the second view: how much would annual revenue change if the share of repeat purchases rose by five percentage points? For most shops the answer is bigger than expected — and cheaper than buying the same volume through ads.
Where retention usually breaks
Not in the tools, in the data. A customer who bought once as a guest and again under a different email address sits in the database twice. The repeat purchase disappears and retention looks worse than it is.
The second common mistake is sending everyone the same thing. A campaign for someone who bought last week and one for someone absent eight months have no reason to be identical.
What it leads to
This is not about stopping acquisition. It is about knowing when the next koruna returns more in an email than in an auction. Everyone can work that number out for themselves — and usually finds it sits somewhere other than they assumed.