AAB vs APK: differences and which to use in 2026

AAB vs APK: which one should you use?

January 12, 2026· 4 min readUpdated June 7, 2026

Short answer: use .aab for the Google Play Store (required since 2021) and APK for sideloading, testing, or alternative stores like Amazon and Samsung.

Definitions

APK (Android Package) — the file Android installs on a device. Self-contained, can be shared and sideloaded.

AAB (Android App Bundle) — a publishing artifact uploaded to Google Play. Play splits it into optimized APKs per device configuration.

Comparison

Aspect	APK	AAB
Installable directly	Yes	No
Required by Google Play (new apps)	No	Yes
Per-device optimization	No	Yes
Typical size delivered to users	Larger	Smaller (15–30%)
Amazon, Samsung, sideload	Yes	No (needs conversion)

Which one should I generate?

For Google Play, generate an .aab. For Amazon Appstore, Samsung Galaxy Store, or sideloading, generate an APK. SaaSToStore can produce both from the same project.

Frequently asked questions

What is the difference between AAB and APK?+

APK is the installable Android package shipped to a device. AAB (Android App Bundle) is a publishing format uploaded to Google Play; the Play Store generates optimized APKs from it for each device.

Which format does Google Play require?+

Since August 2021, all new apps must be published as AAB. APK is still used for sideloading, testing, and stores outside Google Play (Amazon, Samsung).

Can I install an .aab directly on my phone?+

No. AAB is a publishing format. To install on a device, you need an APK extracted from the bundle (via bundletool or the Play Store).

Does an AAB produce smaller APKs?+

Yes. Play uses the bundle to generate device-specific APKs, which are typically 15 to 30 percent smaller than a universal APK.

Can I keep using APK if I prefer?+

Only for sideloading or non-Google stores. The Google Play Store rejects new app submissions that are not AAB.

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