How to Predict Mobile CPI and ROI (ROAS) Based on Current CPM

As a mobile advertising agency focused on user acquisition, we often get the question “What is my CPI going to be?” The answers have gotten more complicated over the years. We always try to drive the conversation towards ROI / ROAS (return on ad spend) and away from pure CPI or CPA. A low cost per install is irrelevant if the quality of the install is poor. However, CPI / CPA is still part of the ROI formula, so it’s worth taking a look at what factors drive it.

Let’s break the CPI and ROAS question down to a few KPIs that you can interactively play with below.

This model is based on a few large channels and geographies. We give you the July 2019 CPM for the combination of:

  • OS (Android/iOS)

  • Country (United States, United Kingdom, Canada, Australia)

  • Source (Facebook, Apple Search, Google Adwords)

You then provide your expected KPIs:

  • CTR (click through rate - clicks/impressions)

  • CVR (conversion rate - installs/clicks)

  • ARPU (Average Revenue per User - hopefully lifetime. If you provide some other period, like 30-day ARPU, your ROAS will be the 30-Day ROAS).

The below workbook will take our inputs and generate your CPI and ROAS (ROI).

Is this useful to you? Would you like see this updated every month? Let me know in the comments or email me at