What is CPM (Cost Per Mille) and How Does It Work?
Cost Per Mille (often abbreviated as CPM or CPT — Cost Per Thousand) is the cornerstone pricing model in digital advertising. In Latin, "Mille" translates directly to one thousand. Therefore, CPM defines the exact price an advertiser pays for every 1,000 views or impressions their ad generates.
The Three Mathematical CPM Formulas
Whether you are planning a media buying budget, reviewing ad network invoices, or estimating inventory requirements, you only need three core equations:
Cost Per Thousand Impressions
Use when you know your total invoice spend and total views delivered.
Campaign Budget Required
Use when forecasting how much cash is needed to reach a desired audience volume.
Total Views Delivered
Use when calculating total potential eyeball reach for a fixed client budget.
Comparison: CPM vs. CPC vs. CPA vs. eCPM
Selecting the right bidding model directly determines campaign profitability. Review how each metric functions:
| Metric | Full Term | You Pay / Earn When... | Ideal Marketing Objective |
|---|---|---|---|
| CPM | Cost Per Mille | Ad is loaded & displayed 1,000 times | Brand awareness, video views, broad reach |
| CPC | Cost Per Click | A user clicks the ad link to visit your website | Traffic generation, search intent, landing page visits |
| CPA | Cost Per Acquisition | A user completes a purchase, form lead, or app install | Direct response e-commerce, leads, subscriptions |
| eCPM | Effective Cost Per Mille | Calculates publisher earnings across all combined monetization units | Website ad revenue, mobile app monetization (AdSense/AdMob) |