eCPM
eCPM is how app publishers compare ad revenue across networks, formats and placements that are paid in different ways. It turns every deal into one number: what 1,000 impressions actually earned.
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Ad networks pay publishers on different models: per impression, per click, per install or per completed view. eCPM normalizes all of them to revenue per thousand impressions, so a banner paid per click and a rewarded video paid per view can be compared side by side.
How eCPM is calculated
Because it is calculated after the fact, eCPM reflects everything that affected earnings: the prices advertisers bid, how often ad requests were filled, and which formats served. It is an average over the period and the placements you selected.
That makes it most useful when you slice it. Compare eCPM by ad unit, by country and by network in the same period, and you can see which placements and demand sources carry the revenue and which ones only add impressions. A blended eCPM for the whole app hides those differences and moves whenever the mix of countries or formats shifts.
eCPM vs CPM
The two use the same arithmetic from opposite sides of the auction. CPM is usually the advertiser’s price: what the buyer pays per 1,000 impressions, either as a bid or as a result. Adapty Ads Manager, for instance, reports Avg CPM for Apple Ads as spend divided by impressions divided by 1,000, and for cost-per-tap campaigns that figure is an effective CPM. eCPM, in publisher reporting, is what the app showing the ads earned per 1,000 impressions, after network fees.
| CPM | eCPM (publisher) | |
|---|---|---|
| Who uses it | Advertisers | Publishers |
| Numerator | Ad spend | Ad revenue earned |
| Typical use | Price of reach | Yield of ad inventory |
| Pricing model | Can be the billing basis | Normalizes any billing basis |
What drives eCPM
- Format. Rewarded video and full-screen formats usually earn more per impression than banners, because users pay more attention to them.
- Country. Advertisers pay very different prices for users in different storefronts.
- Audience and signals. Inventory with richer targeting signals attracts higher bids; privacy restrictions on iOS affect how much advertisers value an impression.
- Fill rate and competition. More demand sources competing for each impression raise the price; unfilled requests earn nothing.
- Seasonality. Advertiser budgets rise and fall through the year, and eCPM moves with them.
Comparing ad revenue with subscription revenue
eCPM on its own does not tell a subscription app whether ads are worth it. To compare the two revenue streams, convert ad earnings into revenue per user over the same period and set it next to subscription revenue per user.
Set that figure against what a paying subscriber is worth, and against the chance that ads push some users away before they reach the paywall. Many apps show ads only to non-paying users and remove them for subscribers, so ad revenue comes from the audience that subscriptions do not monetize. The honest test is incremental: total revenue per cohort with ads versus without.