glossary
eCPM (Effective Cost Per Mille)
eCPM (Effective Cost Per Mille) is the revenue a publisher earns per 1,000 ad impressions, regardless of pricing model. It’s the universal metric for comparing how much money your ad inventory actually makes.
Quick Definition
eCPM (Effective Cost Per Mille) is the revenue a publisher earns per 1,000 ad impressions, regardless of pricing model. It’s the universal metric for comparing how much money your ad inventory actually makes.
What is eCPM?
eCPM translates all your ad revenue into a common language: dollars per thousand impressions.
Your game might run CPC ads, CPA offers, and CPM campaigns all at once. Different pricing models, different payouts. eCPM cuts through that mess and tells you what you’re actually earning per 1,000 impressions across everything.
It’s a publisher metric. While advertisers care about CPM (what they pay), publishers care about eCPM (what they earn).
The difference matters. An advertiser’s CPM bid becomes your eCPM revenue only if their ad wins the auction and performs. eCPM is the real money in your pocket.
How to Calculate eCPM
The formula is simple:
eCPM = (Total Ad Revenue / Total Impressions) × 1,000
Example Calculation
Your game shows 500,000 ad impressions in a day. Those ads generate $1,250 in total revenue.
eCPM = ($1,250 / 500,000) × 1,000 = $2.50
You earned $2.50 per thousand impressions.
This works across any pricing model. CPC campaign paid you $400 for 200,000 impressions? That’s an eCPM of $2.00. CPA offer paid $850 for 300,000 impressions? That’s an eCPM of $2.83.
eCPM lets you compare them directly.
eCPM vs CPM
Both measure cost per thousand impressions. But they’re opposites.
CPM is what advertisers pay. It’s a cost.
eCPM is what publishers earn. It’s revenue.
The Gap Between Them
An advertiser might bid $5.00 CPM. But if their ad doesn’t win every auction, or if your ad network takes a cut, your eCPM could be $3.50.
That gap is where ad networks, mediation platforms, and auction dynamics live.
When CPM = eCPM
Only in pure CPM campaigns where you have direct deals with advertisers. They pay $4.00 CPM, you earn $4.00 eCPM (minus any platform fees).
For CPC and CPA campaigns, eCPM is always calculated backward from actual earnings.
Factors Affecting eCPM
Your eCPM isn’t fixed. It fluctuates based on multiple variables.
1. Geography
US and Japan drive higher eCPMs. Advertisers pay more to reach players in high-value markets.
A rewarded video ad clears $15-$40 eCPM in tier-1 markets like the US, UK, and Japan, but often falls to $3-$10 in tier-2 and tier-3 geos. Same ad format, different audience value.
2. Ad Format
Different formats command different rates:
- Rewarded video: Highest eCPM (players choose to watch)
- Interstitial: Mid-range eCPM (full-screen, high visibility)
- Banner: Lowest eCPM (small, easy to ignore)
3. Placement Quality
Where the ad appears in your game matters. Mid-level completion screens earn more than random pause menu placements. Context drives value.
4. Seasonality
Q4 (holiday shopping season) crushes the rest of the year. Advertisers spend big, eCPMs spike.
January and February? Budgets reset, competition drops, eCPMs fall.
5. Ad Network Competition
More networks bidding on your inventory means higher eCPMs. Single-network setups leave money on the table.
How to Increase eCPM
You can’t control advertiser demand. But you can control how your inventory gets sold.
1. Ad Mediation
Run multiple ad networks and let them compete in real time. Instead of showing a Unity ad every time, let Unity, AppLovin, and ironSource bid against each other.
Higher bids win. You earn more.
2. In-App Bidding
Take mediation further. Instead of waterfalls (testing networks in order), run live auctions where all networks bid simultaneously.
Faster fill, higher eCPMs.
3. Optimize Placement
Bad placements kill eCPM. If players skip your rewarded video 70% of the time, advertisers notice and bid lower.
Put ads where players actually engage with them.
4. Improve Player Quality
High-retention, high-spending players attract premium advertisers. If your game hemorrhages users on Day 1, advertisers won’t pay top dollar for those impressions.
Better game metrics drive better eCPMs.
5. Geographic Targeting
If your game pulls strong US traffic, highlight that to ad networks. Premium geos justify premium inventory pricing.
eCPM Floors
An eCPM floor is the minimum bid required for an ad to show.
Set your floor at $2.00 eCPM? Any ad network bidding below $2.00 gets rejected. Your inventory won’t show ads that don’t hit your price.
Why Use Floors?
Floors protect you from low-value ads tanking your average eCPM. If you know rewarded video in the US typically earns $8 eCPM, setting a $5 floor keeps garbage bids out.
The Risk
Set floors too high and you’ll show fewer ads. Unfilled impressions earn $0. A $3 eCPM is better than no eCPM.
Balance aggressive floors with fill rate. Most mediation platforms let you A/B test floor strategies.
Common Mistakes
Mistake 1: Ignoring Fill Rate
Chasing high eCPM while your fill rate tanks is a losing game. $10 eCPM at 40% fill earns less than $6 eCPM at 90% fill.
Focus on total revenue over eCPM alone.
Mistake 2: Single Network Dependency
Relying on one ad network means no competition. No competition means lower eCPMs.
Diversify your demand sources.
Mistake 3: Treating All Impressions Equally
Not all impressions are worth the same. A rewarded video during a power-up moment is worth 10x a random banner ad.
Optimize your highest-value placements first.
Mistake 4: Setting Floors Without Data
Guessing at eCPM floors kills revenue. Use your historical data. What’s your average eCPM by format, geo, and placement?
Use real data to set floors.
Related Terms
- CPM (Cost Per Mille): What advertisers pay per 1,000 impressions
- CPI (Cost Per Install): What advertisers pay per app install
- ARPDAU (Average Revenue Per Daily Active User): Revenue per daily active user
- Fill Rate: Percentage of ad requests that show ads
- Ad Mediation: Platform managing multiple ad networks
- Waterfall: Sequential ad network testing method
External Resources
Frequently Asked Questions
What is eCPM vs CPM?
CPM is what advertisers pay per 1,000 impressions, a cost. eCPM is what publishers earn per 1,000 impressions, revenue. The gap between them is where ad networks and auction dynamics live.
How do you calculate eCPM?
eCPM = (Total Ad Revenue / Total Impressions) x 1,000. If your game earns $1,250 from 500,000 impressions, your eCPM is $2.50.
What is eCPM in Google Ads?
The math doesn’t change by network. eCPM is the effective revenue per 1,000 impressions your inventory earns, whether the underlying deal was CPC, CPA, or straight CPM.
Should I optimize for eCPM or total revenue?
Total revenue. High fill and volume drive more revenue than a high eCPM with poor fill. eCPM is a diagnostic metric, not the end goal.
