Glossary
What is MAU (monthly active users)?
Monthly active users is the count of unique users who open or interact with a product at least once within a 30-day period.
What MAU is used for
MAU is the standard external scale metric — the number quoted in funding rounds, earnings calls and press coverage — because it is stable, comparable across companies, and large.
Internally it is most useful as the denominator of stickiness and as a smoothed view of reach. It is nearly useless as an operational metric, because a 30-day window responds slowly and blurs whatever caused the change.
The rolling window problem
A rolling 30-day MAU includes anyone active at any point in the window, so a user who used the product once four weeks ago and never returned still counts today.
That gives MAU considerable inertia. A product can lose most of its genuine engagement and hold a flat MAU for a month while the loss works its way through the window. By the time MAU falls, the problem is a month old.
This is why MAU should never be the primary health metric. Retention cohorts show the same deterioration weeks earlier.
What to look at instead
- Cohort retention curves, which reveal changes as they happen rather than after the window clears.
- [DAU](/resources/glossary/daily-active-users-dau)/MAU ratio, which measures depth rather than breadth.
- Engagement distribution within the active base, since MAU treats a daily user and a once-a-month user identically.
- Net new versus reactivated versus retained, which decomposes the number into the three things that actually move it.
Common questions
Is MAU a vanity metric?
It becomes one when reported alone. As the denominator of stickiness, or decomposed into new, retained and reactivated, it is informative.
Calendar month or rolling 30 days?
Rolling is more comparable across periods; calendar is easier to reconcile with financial reporting. Either works — pick one, document it, and do not switch.
More in growth and engagement
Acquiring users, and the behaviour that says whether they stayed.