Net Dollar Retention (NDR) is a metric used to measure the overall health of a subscription-based business. It is calculated by taking the total amount of revenue generated by existing customers in a given period, subtracting any revenue lost from churned customers, and dividing the result by the total amount of revenue generated by those customers in the previous period.
For example, if a company had $100,000 in revenue from its existing customers in the current period, and lost $10,000 in revenue from churned customers, its NDR would be 90% ($100,000 - $10,000 / $100,000).
