What Is eCPM?
eCPM (effective cost per mille) measures the actual revenue or cost per thousand impressions a placement achieved, calculated after the fact rather than a rate agreed upfront. It's the metric publishers, app developers, and networks rely on to compare performance across campaigns priced very differently — CPC, CPA, or CPM.
If a CPC campaign earns $600 from 120,000 impressions, its eCPM is ($600 ÷ 120,000) × 1,000 = $5.00 — directly comparable to a $5.00 CPM deal, even though the two were priced on completely different bases.
eCPM Formula
Divide total revenue by total impressions, then multiply by 1,000.
eCPM = (Total Revenue ÷ Total Impressions) × 1,000
Worked Example
An ad unit earns $420 in revenue from 84,000 impressions.
eCPM = ($420 ÷ 84,000) × 1,000 = $5.00
Rearranged, the formula solves for revenue or impressions instead, which is what the other two modes above do:
Total Revenue = (eCPM × Total Impressions) ÷ 1,000
Total Impressions = (Total Revenue ÷ eCPM) × 1,000
Measuring against total page views or video plays rather than individual ad impressions? Use the RPM calculator instead, or project total earnings with the ad revenue calculator.
What Affects eCPM?
- Fill rate — unfilled ad requests count as impressions with no revenue in some setups, dragging eCPM down.
- Ad network / mediation mix — different networks pay different rates for the same inventory, so the waterfall order matters.
- Viewability — higher-viewability placements typically command better rates from demand-side buyers.
- Audience value — the same impression volume earns more when the audience is more commercially valuable to advertisers.
- Ad format and density — video and rewarded formats typically earn higher eCPM than standard banners, up to a point where too many ads hurt user experience and long-term revenue.
eCPM Calculator FAQ
How is eCPM calculated?
eCPM is calculated by dividing total revenue by total impressions, then multiplying by 1,000: eCPM = (Total Revenue ÷ Total Impressions) × 1,000. Enter your revenue and impressions above to calculate it instantly.
What's the difference between eCPM and CPM?
CPM is the rate agreed or bid upfront, before a campaign runs. eCPM is calculated after the fact from actual realized revenue, which makes it useful for comparing campaigns priced on completely different models — CPC, CPA, or CPM — on one common per-thousand-impressions basis.
Why do publishers and app developers care about eCPM?
eCPM normalizes revenue from different ad networks, formats, and pricing models into a single comparable figure, which makes it the standard way to evaluate which ad units, placements, or mediation partners actually earn the most per thousand impressions.
How do you improve eCPM?
Raise eCPM by improving fill rate, testing higher-paying ad networks or mediation waterfalls, optimizing ad placement and viewability, and adjusting ad density and format mix to find what a given audience responds to and pays best for.