Impression diagnosis
AdMob impressions dropped but eCPM stayed normal
Stable eCPM does not protect revenue if fewer ads are shown. When impressions fall, start with traffic and ad exposure before changing floors, bidders, or mediation settings.
Separate fewer users from fewer ad opportunities
Impressions can fall because DAU or sessions fell, or because active users reached fewer eligible ad moments. Compare impressions per DAU or per session when the data is available.
Check requests, fills, and show rate in order
A request drop points to trigger logic or user activity. Stable requests with fewer impressions can point to fill, readiness, visibility, or show-rate behavior instead.
Find whether the drop is concentrated
Split impressions by country, placement, ad unit, format, app version, and hour. One affected rewarded placement should not be diagnosed as a global eCPM issue.
First checks
- Compare DAU, sessions, and impressions per DAU or session.
- Compare ad requests, fills, show rate, and impressions for the same placement.
- Check recent product releases, frequency rules, and ad trigger logic.
- Split the drop by country, placement, ad unit, format, and app version.
- Compare normal peak hours with the affected hours.
- Review eCPM only after exposure and serving signals are separated.
How to read it
Common interpretation
If eCPM is stable while impressions drop, the most likely driver is lower traffic or ad exposure. A pricing change becomes more likely only after requests, fills, and placement exposure are stable.