How to use the CPI calculator
Enter what you spent and how many installs it brought, and the calculator shows your cost per install. Add what an average installed user is worth to you and the profit you want to keep, and it also shows the highest CPI you can pay and how much room you have left at your current price.
The CPI formula
CPI = ad spend / installs
Installs per $100 = 100 / CPI
Max CPI = revenue per installed user x (1 - profit share you want to keep)Cost per install only tells half the story. An install is worth what the user does afterwards, so the useful number is the gap between your CPI and the most you can afford to pay for that user.
A worked example
A game spends $1,000 and gets 400 installs, a CPI of $2.50. Its average new player brings in $3.00 over their lifetime. To keep 30% of that as profit, the game can pay at most $3.00 x 0.70 = $2.10 per install. At $2.50 it loses $0.40 on every install, so it either needs cheaper installs or more value per player. These figures are illustrative.
Prices differ a lot between countries. Cost per install by country shows how wide the gap is, and setting bids by country explains how to price each market on its own.
How to lower your CPI
- Improve your store page: the icon, the first screenshots, and the rating decide how many visitors install.
- Bid per country instead of one global price, so cheap markets do not pull your average up and expensive ones do not starve.
- Pay for an action after the install, such as finishing the tutorial, when installs alone attract users who never open the app. Task vs offer campaigns covers both ways on Sharklio.
Frequently asked questions
How do you calculate cost per install?
Divide your ad spend by the number of installs. $1,000 spent for 400 installs is a CPI of $2.50.
What is a good CPI?
Any CPI comfortably below what an installed user is worth to you. A $3 CPI is cheap for an app whose users bring in $20 and expensive for one whose users bring in $1.
Is CPI the same as CPA?
CPI is a kind of CPA where the action is an install. CPA can be any action, such as a sign-up, a purchase, or reaching a level in a game.
Why is my CPI higher in some countries?
Competition and user value differ. Advertisers bid more for users in high-income markets, so installs there cost more but are often worth more too.