Marketing
Monthly churn rate from a customer count
The customers lost during the month divided by the customers present at the start of it. This is the base figure every other formula on the page is built from.
The Formula
c = Lost / Start
The customers lost during the month divided by the customers present at the start of it. This is the base figure every other formula on the page is built from.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| Lost | Customers lost during the period | customers | Cancellations plus non-renewals. Should exclude customers who joined and left within the same month if you want a gross rate. |
| Start | Customers at the start of the period | customers | The denominator. It cannot be zero, and it must be the start count or the average count — state which. |
| c | Monthly churn as a decimal | decimal | 0.04 for the 48-of-1200 case. Multiply by 100 to express it as a percentage. |
What Each Symbol Means
Lostcustomers
Customers lost during the period
Cancellations plus non-renewals. Should exclude customers who joined and left within the same month if you want a gross rate.
Startcustomers
Customers at the start of the period
The denominator. It cannot be zero, and it must be the start count or the average count — state which.
cdecimal
Monthly churn as a decimal
0.04 for the 48-of-1200 case. Multiply by 100 to express it as a percentage.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate churn rate page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate Churn Rate, filed under Business. Every number the guide produces comes from substituting into this one line.