Unity — AAB Build Format and 64-bit Support

TL;DR at the bottom of this post.

Android App Bundle (AAB) is the new official publishing format for Android, succeeding the APK.

Compared to the traditional APK expansion file, AAB offers smaller file sizes by leveraging Dynamic Delivery, Google Play's new publishing model.

It strips out code and resources unused by each specific device, allowing users to install lighter and more efficient apps.

AAB is supported in Android Studio 3.2+, Unity 2018.3 and 2017.4.17, and Cocos Creator 2.0.9+.

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In Unity, you can enable AAB with a single checkbox as shown in the image above.

Due to recent Google Play policy changes requiring 64-bit support, build sizes had been increasing. However, AAB builds can largely mitigate this issue.

Beyond size reduction, AAB offers the following advantages over traditional APK:

• Smaller download size and disk allocation
• On devices running Android 6.0+, using uncompressed native libraries stored in the APK reduces download size, disk allocation, and installation time
• Features and configurations can be delivered on-demand when the user requests them, rather than at install time
• No need to build and publish multiple APKs, simplifying build and release management
• When you upload an App Bundle to Play Console, Google Play serves device-optimized binaries:
  • Android 5.0+: Play generates a base APK, configuration APKs, and dynamic feature APKs (if applicable)
  • Below Android 5.0: Play generates multi-APKs server-side

If you are wondering about testing — no need to worry.

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In Unity, just hit Build And Run as shown above, and it installs automatically — no issues there.

Deliver on-demand apps and features with Android App Bundle - Play Console Help

Android Developers

TL;DR: Instead of shipping an APK containing both 64-bit and 32-bit binaries, use the AAB format which automatically selects and installs only the required architecture.