Unit economics
The share of customers who stop buying in a period, and therefore the reciprocal of how long a customer lasts.
Also called Отток
Formula
Churn = Customers lost in period ÷ Customers at start of period
- Customers lost
- measured against a definition of “lost” that is written down before it is counted
Expected lifetime ≈ 1 ÷ churn. Revenue churn and customer churn are different numbers and diverge sharply when the customers who leave are not the ones who spend.
For a business without subscriptions, churn requires an arbitrary decision: how long a silence counts as gone. Whatever is chosen — ninety days, six months, twice the median repurchase interval — it has to be fixed and stated, because every downstream number moves with it.
Revenue churn can be negative: existing customers expanding faster than others leave. A company with negative revenue churn grows without acquiring anyone, which is the strongest position in the model and worth measuring separately.
Dividing this month's losses by this month's larger customer count flatters the rate every month the company grows. Divide by the count at the start of the period, and measure the cohort rather than the pool.
The definitions are the easy part. Whether the figure on your dashboard was computed this way is a different question, and usually the more expensive one.