What is CPM?
CPM, or cost per mille, is the price of 1,000 ad impressions. Mille is Latin for thousand. It is the main pricing unit in programmatic display, video and connected TV, and the easiest way to compare the cost of reaching people across channels, platforms and deals.
When a DSP shows a bid of $6, it almost always means a $6 CPM. You do not pay $6 for one ad, you pay roughly $0.006 per impression.
How is CPM calculated?
The formula is simple:
CPM = total cost / impressions x 1,000
For example, if you spend $500 on 100,000 impressions, your CPM is $500 / 100,000 x 1,000 = $5.
You can flip the formula to plan a budget. Impressions = budget / CPM x 1,000. With a $2,000 budget and an expected $8 CPM, you can expect about 250,000 impressions.
Common CPM variants
Bid CPM: the most you are willing to pay in the auction.
Clearing CPM: what you actually paid. In a first-price auction, the winning bid is the price, so bid strategy has a direct effect on cost.
eCPM: effective CPM, used to compare buys priced another way, such as cost per click, by converting total cost back into a cost per 1,000 impressions.
vCPM: cost per 1,000 viewable impressions, which only counts ads that met a viewability standard.
What drives CPM up or down
Format: video and connected TV usually cost more than standard banners.
Targeting: narrow audiences mean more competition for fewer impressions.
Deal type: private and guaranteed deals often carry higher fixed prices than the open auction.
Market and season: prices vary by country and rise when demand peaks, such as the end-of-year holidays.
Data costs: third-party segments and verification add fees on top of media cost.
Why CPM matters
CPM tells you what reach costs, which is essential for planning and for comparing suppliers. But a low CPM is not automatically good. Cheap impressions are often cheap for a reason: poor placement, low viewability or invalid traffic. A $2 CPM where most ads are never seen can cost more per real result than a $7 CPM on quality inventory.
That is why CPM should sit next to outcome metrics like CPA and ROAS.
CPM vs CPA
CPM is what you pay for exposure. CPA is what you pay for a result, such as a sale or a sign-up. Most programmatic media is bought on a CPM basis, and the bidding is then optimized toward a CPA or ROAS goal. CPM tells you the price of the input, CPA tells you the price of the output. Tracking both over time shows whether rising media costs are actually hurting results.
CPM with AdGeeks
Media in DV360, Amazon DSP and Adform is typically bought on a CPM basis. AdGeeks traders set bids, watch clearing prices and balance CPM against viewability and outcomes, so you pay for impressions that can actually do their job, with no monthly spend minimum.
