CPM Calculator

CPM (cost per mille) is the price an advertiser pays for every 1,000 impressions an ad receives, calculated as ad spend divided by impressions and multiplied by 1,000. "Mille" is Latin for a thousand, which is where the metric gets its name. CPM is widely used for display, video, and awareness campaigns where the goal is reach rather than an immediate click or conversion. It's purely a cost-of-exposure metric: it has no visibility into whether anyone who saw the ad clicked it, remembered it, or did anything else afterward. Skipping the ×1,000 multiplier produces a raw cost-per-impression figure instead, a different and far smaller number that shouldn't be reported as CPM.

Divide ad spend by impressions, then multiply by 1,000: CPM = (Ad Spend ÷ Impressions) × 1,000. A campaign that spent $300 and generated 150,000 impressions has a CPM of ($300 ÷ 150,000) × 1,000 = $2.00. The ×1,000 factor is part of the formula itself, not an optional step; omitting it produces a raw cost-per-impression figure that isn't the same metric and reads as a much smaller, easily-misinterpreted number. Most ad platforms calculate and report CPM automatically, so it rarely needs to be computed by hand. Both the spend and impressions figures should come from the same campaign and reporting window, since mixing periods produces a CPM that doesn't accurately describe either one.

Each measures cost at a different stage of the funnel. CPM is cost per 1,000 impressions: what it cost to be shown, regardless of engagement. CPC is cost per click: what it cost once someone clicked. CPA is cost per defined action: what it cost to get the specific outcome the campaign was paying for, such as a signup or sale. A campaign optimized for reach can post a very low CPM while still carrying a high CPA, since a cheap impression is no guarantee it ever turned into a click, let alone a conversion further downstream.

There's no universal good CPM. It depends on the platform, ad format, audience targeting, and competitiveness of the auction at the time, all of which shift the number before campaign quality even enters the picture. A CPM that looks high on one platform or audience segment can be entirely normal on another with more competitive bidding or a more valuable audience. Track CPM against your own account's history for the same platform, format and audience, which holds the auction context roughly constant. Seasonal demand also moves CPM independent of campaign quality: the same targeting can cost noticeably more during high-competition periods like Q4 than during a quieter month.