What is eCPM?

Effective cost per mille, or eCPM, is the calculated cost per one thousand impressions. To calculate eCPM you must divide the total revenue generated by the total number of ad impressions and then multiplying by one thousand.

What is the difference between CPM and eCPM?

While the calculation for both metrics is the same, there is an important distinction between the two. CPM implies that the cost of the campaign is calculated by the number of impressions. eCPM, however, does not specify a campaign’s cost model. The eCPM metric is a signal of performance.

Let’s use an example. We have two campaigns, “Tiger” and “Fox”. Campaign “Tiger” is using a CPI model. Campaign “Fox” is using a CPM model.

Here are the stats for both:

Tiger
CPI: $1.00
Number of installs: 125
Total cost: $125
Number of ad impressions: 5000
eCPM: $25

Fox
CPM: $25
Number of impressions: 10000
Total cost: $250
eCPM: $25 (eCPM will always be the same as CPM on a campaign that pays per impression)