CPM (Cost per Mille)
CPM (cost per mille) is the price to show your ad 1,000 times — ad spend divided by impressions, multiplied by 1,000.
Formula
CPM = (Ad spend ÷ Impressions) × 1,000
CPM is how most awareness and reach campaigns are priced. If you spend $500 to earn 100,000 impressions, your CPM is $5 — five dollars per thousand views of the ad.
CPM is useful for comparing the cost of reach across platforms and audiences, but a low CPM isn't automatically better: cheap impressions to the wrong audience convert worse than pricier, well-targeted ones. Read CPM alongside CTR and CPC to see whether cheap reach is turning into action.