App version dimension
The app version dimension reports which build of your mobile app a session ran. GA4/Firebase reads it from the app's version string automatically. This page explains how it is populated, why multiple versions coexist in the wild, and how version skew affects event and funnel analysis.
What this means
The app version dimension identifies the specific build of your app — typically the versionName/CFBundleShortVersionString — that produced a session's events. GA4/Firebase captures it automatically from the app, so no manual tagging is needed.
It is the app-world analogue of a browser version: the platform-specific software identity that lets you tie behaviour, errors, and conversions to a particular release.
- Identifies the app build behind a session
- Captured automatically by GA4/Firebase
- App analogue of the browser version dimension
Why version skew matters
Unlike a website, where everyone gets the latest code on load, app users run whatever build they last installed. After a release, traffic is split across the new version and a long tail of older ones until adoption catches up — and some users never update.
This skew shapes analysis. A new event added in version 5.0 simply does not exist in 4.x sessions, so a funnel that assumes it will look broken for older builds. Always segment by app version when comparing features that shipped in a specific release.
- Users run many versions at once after a release
- New events do not exist in older builds
- Segment by version when analysing release-specific features
How it appears in analytics and logs
An app version value names the build behind a session. A spread of versions is normal because users update at different times; a stuck old version can indicate update-adoption problems.
Diagnostic use case
Compare behavior, crashes, and conversions across app versions to confirm a release improved things and to spot regressions tied to a build.
What WebmasterID can help detect
WebmasterID treats app version as event context, so you can segment first-party app behaviour by build without device fingerprinting.
Common mistakes
- Analyzing a new feature without segmenting by app version.
- Assuming all users are on the latest build.
- Reading old-version traffic as a tracking error.
Privacy and accuracy notes
App version is build metadata, not personal data. It describes the software, not the user.
Related pages
- App store dimension
The app store dimension identifies the distribution channel an app came from — Google Play, the Apple App Store, or others. GA4/Firebase captures it for app streams. This page explains how it is populated, how it differs from the platform dimension, and why it is not full install attribution.
- Platform dimension: web, Android, or iOS
Platform is the dimension that records the broad surface a hit came from: web, Android, or iOS. In GA4 it is determined by the data stream the event arrived through, since a property can combine app and web streams. It is coarser than the operating-system dimension and is the right axis for comparing app versus web behaviour — but mixing app-only and web-only metrics across platforms is a frequent reporting error.
- Operating system dimension
The operating system dimension records the platform a visit ran on: Windows, macOS, iOS, Android, Linux, ChromeOS. It is parsed from the user-agent string (and the sec-ch-ua-platform Client Hint), making it a classification rather than a reported fact. Frozen OS versions, iPadOS reporting as macOS, and webviews are the usual reasons it does not perfectly match reality.
- Event Explorer
Segment app events by the build that produced them.
Sources and verification notes
- Google Analytics Help — [GA4] Automatically collected dimensions (app)Lists app version among automatically collected app dimensions.
- Firebase — Automatically collected user propertiesDocuments app version as an automatic property.
Last reviewed 2026-06-24. Facts are checked against primary/official sources where available; uncertain specifics are marked “Data not yet verified” rather than guessed.