Definition
Revenue churn measures recurring revenue lost from existing customers, through cancellations and downgrades, rather than the number of customers lost.
Formula
Gross revenue churn = (churned MRR + contraction MRR) ÷ MRR at the start of the period × 100.
Net revenue churn subtracts expansion; when it's negative, existing customers' revenue is growing.
Customer churn vs revenue churn
Losing ten small customers and one large one are very different. Revenue churn weights losses by what they were worth; customer churn rate counts them equally. Track both.