---
title: Commonly Confused App Metrics Compared Side by Side
description: Side-by-side comparisons of app metrics that are easy to confuse: CPI vs CAC vs CPA, ARPU vs ARPPU, LTV vs ROAS and DAU/MAU vs retention, with calculators.
url: https://appmetricslibrary.com/compare/
---

# Metrics that get mixed up

Side-by-side comparisons, each with a shared calculator.

**Short answer**

Four pairs of metrics that are easy to mix up: CPI, CPA and CAC; ARPU and ARPPU; LTV and ROAS; DAU/MAU and retention. Each page sets the formulas side by side and runs both in one calculator.

Pairs

## Which comparison do you need?

- [**CPI vs CAC vs CPA** Three cost metrics that are often mixed up. Each prices a different step of the funnel, from the install to the paying customer.](https://appmetricslibrary.com/compare/cpi-vs-cac-vs-cpa/)
- [**ARPU vs ARPPU** Two revenue-per-user metrics that differ only in who you divide by, and that can move in opposite directions.](https://appmetricslibrary.com/compare/arpu-vs-arppu/)
- [**LTV vs ROAS** Lifetime value looks forward at what a user is worth; ROAS looks back at what a campaign has earned so far. Read together, they tell you when spend pays back.](https://appmetricslibrary.com/compare/ltv-vs-roas/)
- [**DAU/MAU vs retention rate** Two engagement measures that sound alike and answer different questions: how often active users come back, and how many new users stay at all.](https://appmetricslibrary.com/compare/dau-mau-vs-retention/)

FAQ

## Questions

**Why are these metrics so often confused?**

Because they share a shape: each is a cost or revenue divided by a count of users. The difference is which users are counted and over what time, which is exactly what each comparison sets out.

**What is the difference between a metric and a KPI?**

A metric is any measured quantity; a KPI is a metric a team has chosen as a target for judging performance. Most metrics here become KPIs only for the teams whose work moves them.

**Do I need an MMP to measure these metrics?**

Not for all of them. Engagement and monetisation metrics come from product analytics and billing data, while metrics split by ad channel, such as CPI, ROAS or retention by source, need installs attributed to campaigns.

**Are the calculator's example inputs benchmarks?**

No. The example inputs only make the calculator show a worked answer when the page loads; they are not typical, good or target values. Replace them with your own numbers.

**Does the calculator send my numbers anywhere?**

No. It runs entirely in your browser, and nothing you type is stored or sent anywhere.