Cost per thousand impressions — solve for CPM, for total cost, or for how many impressions your budget will buy.
CPM stands for cost per mille — the price of 1,000 ad impressions. It is how most display, video, and social inventory is priced, and the easiest way to compare the cost of reaching an audience across platforms.
A campaign cost $2,500 and served 400,000 impressions. CPM = 2,500 ÷ 400,000 × 1,000 = $6.25.
If a publisher quotes a $12 CPM and you want 250,000 impressions, the campaign costs 12 × 250,000 ÷ 1,000 = $3,000. With a $5,000 budget at that CPM you can buy 5,000 ÷ 12 × 1,000 = 416,666 impressions (rounded down). Use the modes above to do either.
CPM varies by platform, placement, audience, and season — CPMs typically rise sharply in Q4 as retail advertisers compete for the same inventory. A cheaper CPM is only better if those impressions still turn into clicks and sales, so read CPM alongside CTR and CPA.
What does CPM stand for? Cost per mille — "mille" is Latin for thousand. It is the cost of 1,000 ad impressions.
How do you calculate CPM? Divide total ad spend by total impressions and multiply by 1,000. $2,500 for 400,000 impressions is a $6.25 CPM.
How do you convert CPM to CPC? CPC = CPM ÷ (CTR × 1,000). At a $6.25 CPM and a 1% click-through rate, each click costs $0.63.
