测量你的应用体积

Many developers are concerned with the size of their compiled apps. As the APK, app bundle, or IPA version of a Flutter app is self contained, and holds all the code and assets needed to run the app, its size can be a concern. The larger an app, the more space it requires on a device, and the longer it takes to download, and it may break the limit of useful features like Android instant apps.

By default, launching your app with flutter run, or by clicking the Play button in your IDE (as used in Test drive and Write your first Flutter app), generates a debug build of the Flutter app. The app size of a debug build is large due to the debugging overhead that allows for hot reload and source level debugging.

To get a better sense of what an end-user actually has to download for a Flutter app, use the following instructions.

Android

Run the following from the top of your Flutter project to get the size of APK for 32-bit Android devices:

flutter build apk --target-platform=android-arm

The output should look something like the following:

Built build/app/outputs/apk/release/app-release.apk (4.2MB).

For 64-bit Android devices, run the following:

flutter build apk --target-platform=android-arm64

Here is an example output:

Built build/app/outputs/apk/release/app-release.apk (4.6MB).

As of Flutter 1.9, you can run the following to get 2 APKs, one for 32-bit and one for 64-bit:

flutter build apk --split-per-abi

Here’s some sample output:

Built build/app/outputs/apk/release/app-armeabi-v7a-release.apk (4.2MB).
Built build/app/outputs/apk/release/app-arm64-v8a-release.apk (4.6MB).

iOS

To get a rough idea of how large your release IPA is, run the following:

flutter build ios && tar -zcf build/app.ipa build/ios/iphoneos/Runner.app && ls -lh build/app.ipa

The resulting IPA file for the example/helloworld app (as of this writing) is 8.3 MB.

-rw-r--r--  1 userName  primarygroup   8.3M Oct 25 13:47 build/app.ipa

To measure an iOS app exactly, you have to upload a release IPA to Apple’s App Store Connect (instructions) and obtain the size report from there. IPAs are commonly larger than APKs as explained in How big is the Flutter engine?, a section in the Flutter FAQ.

Reducing app size

Some of the obvious things you can do to make your app smaller are:

  • Remove unused resources
  • Minimize resource imported from libraries
  • Support a limited number of screen densities
  • Compress PNG and JPEG files