eCPM: Effective cost per mille (effective revenue per thousand impressions).

When a mobile game shows ads, eCPM is how the team tells whether those ads are earning well. It turns revenue from clicks, installs, views and impressions into one comparable number: dollars per thousand impressions.

The eCPM formula

eCPM = ad revenue ÷ ad impressions × 1,000

It is "effective" because advertisers may pay per click, per install or per completed view. Dividing what you actually earned by what you actually showed puts everything on one scale.

A worked example

On one day, a puzzle game shows 15,000 ads and earns $90.

eCPM = $90 ÷ 15,000 × 1,000 = $6.00

Split by format, the same day looks like this:

Format	Impressions	Revenue	eCPM
Rewarded video	5,000	$60	$60 ÷ 5,000 × 1,000 = $12.00
Interstitial	6,000	$27	$27 ÷ 6,000 × 1,000 = $4.50
Banner	4,000	$3	$3 ÷ 4,000 × 1,000 = $0.75
Total	15,000	$90	$6.00

Rewarded video earns 16 times what a banner does per impression in this example. The exact gap varies, but this order (rewarded, then interstitial, then banner) is typical, because a player who chooses to watch a full-screen video is worth more to advertisers.

How eCPM links to ARPDAU

Ad revenue per daily active user = impressions per DAU × eCPM ÷ 1,000

If the game above had 3,000 daily active users, each saw 15,000 ÷ 3,000 = 5 ads. Ad ARPDAU = 5 × $6.00 ÷ 1,000 = $0.03.

So there are two ways to raise ad revenue: show more ads per player, or earn more per ad. Showing more ads can hurt retention; earning more per ad usually does not. That is why teams work so hard on eCPM. See ARPDAU for the full revenue picture.

What affects eCPM

• Ad format. Rewarded and full-screen formats earn more than banners.
• Country. Players in high-income markets such as the US usually command much higher eCPMs than players in lower-income markets.
• Platform. iOS often earns more than Android, though the gap varies by market.
• Season. Advertisers spend more in the last quarter of the year, so eCPMs often rise before the holidays and drop in January.
• Mediation and bidding. Running several networks in a mediation platform, with in-app bidding, lets them compete for each impression.
• Fill rate. If no network fills a request, you earn nothing for it.
• Player data and consent. Where users allow personalized ads, eCPMs are often higher.

eCPM for advertisers

On the buying side, eCPM means what an advertiser effectively paid per thousand impressions. It is linked to cost per install through IPM: CPI = CPM ÷ IPM. The same term is used on both sides of the market, so make sure you know which side a report is written from.

How to raise eCPM

1. Use rewarded ads well. Place them where players want help: a continue after failing, double rewards, a free spin.
2. Add networks through mediation. More competition per impression usually means higher prices.
3. Set sensible price floors. Floors that are too high cut fill rate; too low leave money on the table. Test them by country.
4. Keep the experience clean. Networks value placements where players actually watch. Spammy placements can lower prices over time.
5. Watch the mix. If eCPM falls, check whether it is the ads or simply more players from lower-eCPM countries.

See our ads and monetization service for help with mediation and ad placement.