CPM, or Cost per Thousand, is a measurement of the cost of advertising on a marketing campaign.
Per Impression Cost = Campaign Cost / Impressions
CPM = Per Impression Cost x 1000
A marketing campaign costs $500 and generates 3,000,000 impressions.
CPM = ($500 / 3,000,000) x 1000 = 0.0001667 x 1000 = 0.17
Therefore, this marketing campaign has a CPM of $0.17.