What is ARPDAU?

Why daily

ARPU over a month blends users with wildly different engagement and takes a month to tell you anything. ARPDAU normalises to a single day, which makes it comparable across periods of different lengths and fast enough to act on.

That responsiveness is the point. A monetisation change, a new ad placement or a pricing test shows up in ARPDAU within days, which is why it is the number on the dashboard rather than in the quarterly review.

How to read a change

ARPDAU moves for reasons that require opposite responses, and the ratio alone does not distinguish them.

It rises when monetisation genuinely improves — and also when low-engagement users churn, shrinking the denominator. A rising ARPDAU alongside falling DAU is usually a warning rather than a win.

It falls when a marketing campaign brings a wave of new users who have not yet monetised, which is normal and temporary. It also falls when an ad placement is removed, which may be a deliberate trade for retention.

The discipline is to read it alongside DAU and retention rather than on its own.

ARPDAU for AI applications

• Split by revenue type. Advertising and subscription behave differently and should not be averaged.
• Watch it against session length. Advertising that raises ARPDAU while shortening sessions is borrowing from tomorrow.
• Consider per-query revenue as well. For conversational products, revenue per query often describes the economics more directly than a per-user figure.
• Cohort it by acquisition source, or a change in traffic mix will read as a change in monetisation.