Cost Per Mille (CPM)

CPM (cost per mille) is the inventory-pricing model in digital advertising: the price an advertiser pays for 1,000 ad impressions, regardless of whether those impressions drive clicks, installs, or any downstream action. "Mille" is Latin for 1,000. It's the original pricing model from print and broadcast — and remains the unit of inventory pricing on programmatic ad exchanges.

CPM ranges vary wildly

• Low-tier Android bannerGlossaryBanner AdA small persistent ad shown at the top or bottom of the app screen — the lowest-attention and lowest-eCPM mobile ad format, but high in impression volume. inventory in emerging markets: $0.30-1.50
• US iOS rewarded videoGlossaryRewarded VideoA video ad format that users opt-into voluntarily in exchange for an in-app reward (currency, lives, extra content). The highest-eCPM mobile ad format because the us...: $10-25
• US iOS premium interstitialGlossaryInterstitial AdA full-screen ad format shown between app sessions, level transitions, or natural break points. Forced-view (unlike rewarded video), so timing and frequency are crit... in financial content: $25-50+
• Connected-TV / OTTGlossaryOver-the-Top (OTT)The delivery of video content directly over the internet, bypassing traditional cable/satellite distributors — and the advertising channel that streaming creates. mobile in-app premium: $30-80

Drivers: geography (audience purchase power), platform (iOS premium), format (video > interstitial > banner), and inventory quality (premium content app inventory > casual game inventory > random programmatic inventory).

CPM vs eCPMGlossaryeCPM (Effective Cost Per Mille)The revenue a publisher actually earns per 1,000 ad impressions — the publisher-side counterpart to CPM, after auction dynamics, fill rates, and floor prices. — easy to confuse:

• CPM is buyer-side: what an advertiser pays for inventory.
• eCPM is publisher-side: revenue per 1,000 impressions that a publisher actually realizes after auction dynamics, fill rates, and floors.

For a perfectly-cleared auction with no friction, CPM = eCPM. In practice they diverge because of fill rates (not every impressionGlossaryAd ImpressionA single instance of an ad being served to a user — the atomic unit of ad inventory. What counts as "served" vs "viewable" vs "verified" matters enormously for pricing. sells), auction floor mechanics, ad-network take rate.

When CPM bidding makes sense for performance UAGlossaryPaid UA (Paid User Acquisition)Mobile app user acquisition via paid advertising channels — Meta, TikTok, Google, AppLovin, ironSource, and other ad networks.: rarely. CPM bidding pays for views even if no installs result, so you bear all the inventory risk. The performance equivalents — CPIGlossaryCost Per Install (CPI)The average amount an advertiser pays for a single install attributed to a campaign — total spend divided by attributed installs. bidding (pay per install), CPAGlossaryCost Per Action (CPA)The cost of acquiring one user who completes a defined action — registration, trial start, first purchase — rather than just installing. Always higher than CPI. bidding (pay per action), ROASGlossaryROAS (Return On Ad Spend)Campaign revenue divided by campaign cost over a defined time window — the core profitability ratio for paid user acquisition. bidding (target return) — shift risk to the network. CPM bidding is mostly appropriate for brand campaigns where impression delivery itself is the goal (awareness, reach), not downstream conversion.