Net dollar retention answers whether a business would grow if it stopped acquiring customers entirely. For subscription businesses, it is the most informative single metric in the reporting package, and investors treat it accordingly.
The calculation takes beginning annual recurring revenue, adds expansion, subtracts contraction and churn, then divides by beginning ARR. A company opening a period with $2,000,000 in ARR that gains $340,000 in expansion, loses $85,000 to contraction, and loses $145,000 to churn ends at $2,110,000. Divided by the opening figure, NDR is 105.5%.
New customers acquired during the period are deliberately excluded. Including them would measure total growth rather than the health of the existing base, which is the entire point of the metric.
Reading the result is straightforward. Above 100% means expansion exceeded losses, so the customer base grew without any new acquisition. This is the threshold separating businesses with compounding revenue from those that must acquire continuously just to stay level. At exactly 100%, expansion offsets losses and all growth must come from new acquisition. Below 100%, the existing base is shrinking and new acquisition is filling a leaking bucket, which means the effective cost of acquisition is higher than it appears.
Strong SaaS businesses report NDR between 110% and 130%. Companies serving enterprise customers with expansion-friendly pricing, whether per-seat, usage-based, or tiered, regularly exceed 120%. Products focused on small businesses typically report lower figures because smaller customers churn more often and expand less. At 120%, a cohort worth $1 million grows to $1.2 million across a year with no new sales activity, which compounds substantially over several years.
Gross dollar retention measures the same base but excludes expansion, capturing only what was retained. It cannot exceed 100%. The gap between the two figures reveals how much expansion is offsetting losses. A company reporting 115% NDR alongside 85% GDR has strong expansion masking meaningful churn. A company reporting 115% NDR alongside 105% GDR has both working. Investors request both figures for exactly this reason, because NDR alone can conceal a retention problem.
Improving the number comes down to four levers. Expansion pricing means structuring the product so customer growth drives revenue growth without requiring a sales conversation. Onboarding matters because customers who reach initial value quickly churn less, making time-to-first-value one of the strongest retention predictors. Churn signals such as declining usage and reduced login frequency typically precede cancellation by months, creating intervention time when monitored. Contract structure also affects the result, since annual agreements with usage-based expansion produce higher NDR than month-to-month arrangements at equivalent pricing.
Calculating NDR accurately requires revenue organized by customer cohort with expansion, contraction, and churn tracked separately. A general ledger recording total subscription revenue without customer-level detail cannot produce a reliable figure.