Net revenue retention (NRR)

Revenue from a cohort of customers today divided by that same cohort's revenue a year ago, including expansion, contraction, and churn. Above 100% means the base grows without new logos. Restated as net revenue churn, the ideal state is negative net churn: expansion outpacing everything lost.

NRR = (Starting ARR + Expansion - Contraction - Churn) / Starting ARR

Measure it two ways: uncohorted (a blended trailing window, the headline number) and by cohort (each start-period group tracked separately), because a strong blended NRR can ride on old cohorts while new ones decay.