Product metrics and goals
Churn rate
Also called Customer churn, Logo churn, Attrition
The share of customers who leave in a period. The mirror image of retention, and the number that most limits how big a subscription business can get.
How it's worked out
Customers who cancelled in the period ÷ customers at the start of the period × 100
Monthly churn compounds: losing 5% a month means losing nearly half your customers in a year. Small improvements are worth a lot.
Look at it by cohort and by reason. Customers who leave in the first month usually never activated; customers who leave after a year usually found the product stopped meeting a need.
In practice
A product starts the month with 1,200 customers and 24 cancel: monthly churn is 2%.
Common mistake
Mixing up customer churn and revenue churn. Losing many small customers and a few big ones gives very different pictures.