What Is eCPM? (Effective Revenue per Thousand Impressions)
The revenue your app earns per thousand ad impressions — the core revenue metric on the publisher side.
Book a free calleCPM (effective cost per mille) is the effective revenue an app earns per thousand ad impressions. It's calculated as (Total Ad Revenue ÷ Impressions) × 1,000. While CPM is the cost the advertiser pays, eCPM is the revenue the publisher earns; it lets you compare different ad networks and ad formats on the same scale.
How do you calculate eCPM?
That's where the "effective" in eCPM comes from: even if one ad network pays on a CPC basis and another on CPI, converting both to eCPM lets you compare them directly.
What determines eCPM?
- Ad format: Rewarded video and interstitials generate far higher eCPMs than banners.
- User geography: Traffic from the US, Japan and Western Europe is worth several times more than traffic from emerging markets.
- Platform: iOS inventory generally commands higher eCPMs than Android.
- User quality: Highly engaged audiences with a propensity to spend are more valuable.
- Demand competition: The more networks bidding on your inventory, the higher the price.
- Seasonality: eCPMs rise at year-end and during shopping seasons as ad budgets increase.
eCPM floor management
An eCPM floor (price floor) is the minimum price at which you're willing to sell your inventory. Set correctly, it lifts revenue significantly; set incorrectly, it causes serious losses.
| Floor level | Outcome |
|---|---|
| Too low | Inventory sells cheap, revenue is left on the table |
| Optimal | Fill rate and price are balanced, revenue is maximized |
| Too high | Impressions go unfilled, fill rate drops, total revenue falls |
That's why eCPM shouldn't be optimized in isolation. A high eCPM with a low fill rate can generate less revenue than a low eCPM with a high fill rate. The composite metric to track is ARPDAU.
How do you increase eCPM?
- Switch to in-app bidding. Instead of a traditional waterfall, a real-time auction has networks compete simultaneously and pushes prices up.
- Diversify demand sources. More ad networks and DSPs mean more competition for your inventory.
- Lean into high-value formats. Rewarded video is one of the highest-eCPM formats that doesn't hurt the user experience.
- Optimize placement and timing. Ads shown at natural breaks perform better and don't increase churn.
- Set floors by geography. A single global price floor loses revenue in high-value markets.
- Monitor ad quality. Intrusive or misleading ads may bring in revenue short-term, but they hurt retention and cost you in the long run.
Frequently asked questions
What's the difference between eCPM and CPM?
CPM is the cost the advertiser pays per thousand impressions; eCPM is the revenue the publisher earns per thousand impressions. They're two sides of the same transaction, and the gap between them comes from platform and intermediary fees. Advertisers try to lower CPM; publishers try to raise eCPM.
Is a high eCPM always good?
No. You can raise eCPM by pushing the price floor very high, but if most impressions go unfilled, total revenue drops. The right optimization target isn't eCPM but the ARPDAU it produces together with fill rate.
Should you use waterfall or bidding?
In most cases in-app bidding delivers better results: because networks compete simultaneously and in real time, price discovery is more efficient and the burden of manual floor management goes down. Hybrid setups are still used to keep certain demand sources that can't move to bidding.
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