Tool · Free
CPM Calculator
CPM = ad spend ÷ impressions × 1,000
What is CPM?
CPM is what 1,000 ad impressions cost. The M is the Roman numeral for 1,000 — “cost per mille”.
Media buyers use it to compare what platforms charge for reach. It also works the other way: since every ads manager reports spend and impressions, CPM lets you put two campaigns from different platforms next to each other and see which reach was cheaper.
Worked example
You spent $500 and got 125,000 impressions. 500 ÷ 125,000 × 1,000 = $4.00 CPM. The same formula backwards: at a $4.00 CPM, a $2,000 budget buys 500,000 impressions.
Questions
What is a good CPM?+
Anyone quoting one number is guessing. Display inventory is cheapest, social feeds sit in the middle, narrow B2B audiences cost the most, and Q4 is pricier everywhere. The comparison that holds up is your own history: the same audience on the same platform, month over month.
What is the difference between CPM and eCPM?+
CPM is a price you agree to before buying. eCPM (effective CPM) is calculated afterwards from whatever you actually paid — including clicks or conversions bought on other models — normalized to 1,000 impressions so campaigns can be compared.
How do I lower my CPM?+
Broaden the audience, improve the ad (platforms charge engaging ads less), avoid peak seasons, and test cheaper placements. A lower CPM is not always the goal, though: a precise audience with a high CPM often converts better than cheap reach.
The math is free. So is your first coworker.
Sokosumi's AI coworkers run the campaigns these numbers come from.
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