How to decrease app Size in flutter?

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GYTWorkz

4 min readJul 13, 2022

App size is important for applications. It has two dimensions: the download size (the size of the app on the play store/when downloading/when installing) and the install size (what happens when you download the app, unpack it, compile it, and optimise it). This significantly expands the application and can be two, three, or even four times the size of the install.

Analyze your app size

It includes native code, assets, and even a breakdown of the compiled Dart code at the package level. We can analyse app size using the following commands for the specific platform.

For Android’s AppBundle,

flutter build appbundle --target-platform android-arm --analyze-size
flutter build appbundle --target-platform android-arm64 --analyze-size
flutter build appbundle --target-platform android-x64 --analyze-size

For Android’s APK,

flutter build apk --target-platform android-arm --analyze-size
flutter build apk --target-platform android-arm64 --analyze-size
flutter build apk --target-platform android-x64 --analyze-size

For iOS,

flutter build ios --analyze-size

For Linux,

flutter build linux --analyze-size

For macOS,

flutter build macos --analyze-size

For Windows,

flutter build windows --analyze-size

DevTools

It can be used to see a visual representation of it.

To activate the devtools run the following command,

flutter pub global activate devtools

To see the visual representation of the app,

flutter pub global run devtools --appSizeBase=apk-code-size-analysis_01.json

Remove unused resources

There are manual and automatic methods for deleting unwanted resources.
You can use manual approaches by deleting the files you don’t require.

Automatic method can be approached by Android studio follow the given steps below :

Right Click Project.
Pick Refactor from the menu.
Select Remove Unused Resources from the menu.

Minimize resource imported from libraries

Once your app has been built, you should review your pubspec.yaml and delete any unnecessary libraries or packages.

Compress PNG and JPEG files

When we need to use images in-app, such as a tutorial mode screen, and we don’t want to call the images from an external storage, we should compress our PNGs and JPGs because high-quality images will bloat the app size.

Fonts

If we are using more fonts from local assets similar like images these fonts will also increase app size. The best solution is to use google_fonts plugin. This pluign will dynamically download font when it is used.

Proguard (for Android Only)

Proguard is a Java application optimization tool. It isn’t just for Flutter. It shrinks your code by altering the representation rather than the functionality. When the original name for types, fields, and methods is unimportant, long names are replaced by short strings like a and b to save time. Even though classes and programmes may have lengthy names, they should not be ineffective. It also removes all unnecessary Java code from dependencies.

We have two default proguard files that we can use,

proguard-android-optimize.txt — progurard configuration
proguard-android.txt

The default proguard configuration that we utilised was proguard-android-optimize.txt. In your /app directory’s proguard-rules.pro file, we can add your own proguard configurations.

release {
    //Enable the proguard
    minifyEnabled true
    proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), "proguard-rules.pro"

    //Other parameters
    debuggable false
    jniDebuggable false
    renderscriptDebuggable false
    signingConfig playStoreConfig //Add your own signing config
    pseudoLocalesEnabled false
    zipAlignEnabled true
}

The proguard will eliminate all unneeded methods, instructions, and classes by setting minifyEnabled to true. file dex. We may reduce the classes by enabling on Proguard in each module of our project. dex file size by roughly half.

Split Bundle (for Android Only)

If we are uploading to the Playstore, we could create an app bundle, or we could split the apk per abi, which splits the apk into x64 and x86 bit code. Using appbundle, Google Play’s new app serving model, called Dynamic Delivery, uses your app bundle to generate and serve optimised APKs for each user’s device configuration, ensuring that they only download the code and resources required to run your app.

flutter build apk --split-per-abi

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