Expansion revenue counts every dollar an existing account adds after its first invoice — seat expansion, tier upgrades, and metered overage. Measure it monthly against the same cohort’s opening balance, and keep it apart from new-logo bookings so that neither one masks the other inside a single growth figure. Most finance teams report it net of any mid-cycle downgrade, then hold that series steady for at least four consecutive closes.
Expansion revenue shows how much value an account keeps finding after onboarding, which is why it sits beside net retention, gross churn, and payback period on a board deck. A team that grows inside its existing base can absorb a slow quarter of new sales without rewriting its forecast, and it tends to renew on far friendlier terms.
Start with usage signals, price the tier your heaviest accounts already outgrew, and give owners a self-serve path to add seats. Reviewed each quarter against renewal dates, those three moves tend to move the number further than another outbound push.