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Definition

Effective Cost Per Mille

The estimated earnings a publisher receives for every 1,000 ad impressions served, accounting for all types of revenue.

Effective Cost Per Mille (eCPM) is an essential metric that allows publishers to compare revenue generated across different ad units, campaigns, and monetization strategies, regardless of whether they are based on clicks, impressions, or conversions.

eCPM vs. CPM

While CPM is the cost an advertiser pays for 1,000 impressions, eCPM is what the publisher actually earns per 1,000 impressions. eCPM is a “normalized” metric that helps you understand the true value of your traffic.

How to calculate eCPM

The formula for eCPM is:

(Total Revenue / Total Impressions) * 1,000

For example, if a campaign earned you $50 from a total of 25,000 impressions, the eCPM would be $2.00.

Why publishers use eCPM

  • Comparing Networks: It helps you see which ad network is performing better relative to the traffic you send them.
  • Optimizing Layouts: You can determine which ad positions on your page are most profitable.
  • Revenue Forecasting: It provides a reliable baseline for estimating future earnings based on traffic growth.

Monetise your website without the clutter

Inset helps small publishers and niche sites earn more through premium, non-disruptive promotions. High eCPMs, easy setup, and respect for your audience.

Last updated: January 27, 2026