Churn Acceleration
The second derivative of churn — whether your churn rate is quietly speeding up before the level alarms anyone.
What is it?
Churn Acceleration is the change in your churn rate from one period to the next — the second derivative of churn. A churn rate can look stable at 6% while quietly climbing half a point a month; acceleration is what surfaces that before the level itself alarms anyone.
It reframes churn as a trajectory, not a snapshot. A modest churn rate that is accelerating is a bigger problem than a higher one that is flat and falling, because acceleration compounds.
How to calculate?
Subtract last period's churn rate from this period's. A move from 5.8% to 6.2% is a churn acceleration of +0.4 points. Because it is a difference of already-noisy rates, read it on smoothed inputs rather than raw month-to-month figures.
Watch the sign and the streak: one positive month is noise, three in a row is a trend worth tracing to whichever cohort or segment is deteriorating.