What eCPM means
eCPM (effective cost per mille) is the estimated earnings for every 1,000 ad impressions. It rolls up all ad formats and pricing models — including impression-based and click-based ads — into one comparable number. The formula is simple:
eCPM = (earnings ÷ impressions) × 1000
And to project revenue from traffic:
revenue = impressions × eCPM ÷ 1000
where impressions = DAU × impressions per user × fill rate.
A realistic word of caution
These figures are planning estimates, not guarantees. Real eCPM swings widely with the user's country, the ad format (rewarded and interstitial usually pay more than banners), seasonality (Q4 is higher), fill rate, and mediation setup. Traffic from the US and Western Europe typically earns several times more per impression than traffic from many other regions. Treat the output as a range, and validate against your actual AdMob reports.
Tips to raise eCPM
- Use higher-value formats (rewarded, native, interstitial) where they fit the experience.
- Add mediation so multiple networks compete for each impression.
- Keep fill rate high and place ads where they are actually viewable.
- Segment by geography — the same app can have very different eCPM per country.
FAQ
What's the difference between eCPM and RPM?
They are calculated the same way — earnings per 1,000 units — but RPM (page/session RPM) is often used for web/pages, while eCPM is the standard term for ad impressions in apps.
Is fill rate the same as impressions?
No. Fill rate is the share of ad requests that actually return an ad. If you request 5,000 ads and 4,500 are filled, the fill rate is 90%. Only filled ads become impressions.
Why is my real revenue different from this estimate?
Because eCPM is not fixed. It changes daily with demand, geography, format and season. Use your own recent eCPM from AdMob for the closest projection.
Does this tool send my numbers anywhere?
No. All math runs locally in your browser and nothing is uploaded.
What actually drives your eCPM
Two apps with identical download numbers can earn very differently, and eCPM is where that difference shows up. The biggest lever is geography: an impression served to a user in the US or Western Europe can be worth several times one served elsewhere, purely because advertisers bid more for those audiences. After that comes format — rewarded video and interstitials generally command higher rates than banners because they command more attention — and fill rate, the share of ad requests that actually return a paid ad. Seasonality matters too: budgets swell in Q4, so the same app often posts its best eCPM in November and December.
Using this estimate responsibly
The point of a projection like this is to sanity-check a plan, not to promise a payout. If a rough model says a feature can't move revenue meaningfully even under optimistic assumptions, that's useful before you build it. But treat every output as a range and replace the assumptions with your own recent AdMob numbers as soon as you have them — your real eCPM, your real fill rate, your real geographic split. A forecast built on your actual last-30-days figures is far closer to reality than any generic benchmark.
Impressions per user is the quiet variable
People focus on eCPM and forget that revenue scales just as directly with how many ad impressions each session produces. Doubling impressions per user doubles projected revenue at the same eCPM — but push it too far and you damage retention, which shrinks the very audience generating those impressions. The healthy target is the point where an extra ad placement adds revenue without measurably hurting how long people keep using the app, and that balance is worth testing rather than guessing.