CPE stands for Cost Per Engagement. CPE is calculated by dividing the advertising cost by the number of engagements.
CPE = Advertising cost / Number of engagements
CPE is a pricing model used by advertisers whereby they choose a post-install event to pay once the user engages with the app. In the CPE model, the advertiser can choose to pay if the users reach certain events like writing reviews, reaching a certain stage etc.