What Is eCPM? A Plain-English Guide for App Developers
eCPM is the single most important number in ad monetization — yet it's widely misunderstood. Here's the plain-English version.
The one-sentence definition
eCPM stands for effective cost per mille — the revenue you earn for every 1,000 ad impressions. (“Mille” is Latin for thousand.) It’s the most useful number in ad monetization because it puts every ad, deal, and network on the same scale.
The formula
eCPM = (Total ad revenue ÷ Total impressions) × 1,000
Earn $50 from 20,000 impressions and your eCPM is ($50 ÷ 20,000) × 1,000 = $2.50. Flip it around to forecast revenue: impressions ÷ 1,000 × eCPM.
Why “effective”?
Your impressions might be filled by many deal types — fixed CPM buys, cost-per-click, cost-per-install campaigns, even house ads. eCPM blends them all into one comparable per-thousand figure, so you can judge a placement or network without untangling how each impression was sold.
eCPM vs CPM vs RPM
- CPM is what an advertiser agrees to pay per 1,000 impressions. eCPM is what you actually earned, after fill and blending.
- RPM (revenue per mille) is the web equivalent, measured per 1,000 pageviews rather than impressions.
- CPC / CPI price single clicks or installs; eCPM lets you compare them against impression-based ads.
What moves your eCPM
- Ad format — rewarded video can earn 10×+ what a banner does.
- Geography — US/UK/AU users command far higher eCPMs than emerging markets.
- Season — eCPMs spike in Q4 as advertisers spend holiday budgets.
- Category & platform — finance apps and iOS users skew higher.
How to use it
Track eCPM by format, geo, and network and you’ll quickly see where your revenue actually comes from — and where a small change pays off. New to the formats? Compare rewarded video vs interstitials next.
Calculate your estimated earnings →
Ready to monetize?
Apply to the networks that fit your platform — most are free and approve within a few days.
The most popular mobile ad network. Free to start, massive advertiser demand, and easy SDK integration.
Apply to AdMob →The go-to ad network for websites and blogs. Quick approval, reliable payments, and Google's full demand.
Apply to AdSense →Top-paying mediation platform. Runs a real-time auction across all major networks to maximize your eCPM.
Apply to AppLovin MAX →Put real numbers on it
Use the free calculator to estimate your revenue across every major ad network.
Keep reading
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Read guideHow Much Do Mobile Ads Actually Pay? Real eCPM Ranges by Network
"How much will I make from ads?" depends on format, geo, and network. Here are realistic eCPM ranges to anchor your expectations.
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