MAU
Monthly Active User — a user who took at least one qualifying action in the last 30 days. The most common metric for engagement.
MAU stands for Monthly Active User: someone who took at least one qualifying action (opening the app, sending a message, whatever the product decides counts) within the last 30 days. It's the most-cited engagement metric in SaaS.
The definition of "active" is subjective and matters. Some products count any login as active; others require a real product action (sent message, created document, made purchase). Products with weak retention have an incentive to define active loosely; products with strong retention can afford a stricter definition.
MAU is a lagging indicator. If your product has a churn problem, MAU won't drop for weeks — the users you already have keep being active until they stop. Better teams pair MAU with: - **DAU (Daily Active User)**: catches drops faster. - **DAU/MAU ratio**: shows stickiness. 20% means users log in about 6 days a month; 50% means most users are on it half the days of the month. - **Retention curves**: what percentage of users from cohort X are still active at week 4, week 12, week 24?
MAU can also inflate quickly with acquisition — a growing MAU number can mask a declining retention problem if the new-user flow is strong enough. Any single-metric read on engagement is misleading; watch MAU alongside cohort retention.