App size optimization in Android Kotlin

Introduction

App size optimization helps make your app smaller. Smaller apps download faster and use less space on phones.

When your app is too large and users complain about download time.

When you want to reduce data usage for users with limited internet.

When you want to improve app install rates on devices with low storage.

When you add many images or libraries and want to keep app size small.

Syntax

Android Kotlin

android {
    defaultConfig {
    }
    buildTypes {
        release {
            // Enable shrinking and obfuscation
            minifyEnabled true
            // Remove unused resources
            shrinkResources true
            // Use ProGuard or R8 rules
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
}

minifyEnabled removes unused code and obfuscates names.

shrinkResources removes unused resources like images and strings.

Examples

Disables code shrinking and resource shrinking. App size will be larger.

Android Kotlin

minifyEnabled false
shrinkResources false

Only code shrinking is enabled. Resources are not removed.

Android Kotlin

minifyEnabled true
shrinkResources false

Both code and resource shrinking are enabled. Best for smaller app size.

Android Kotlin

minifyEnabled true
shrinkResources true

Sample App

This is a minimal Android app setup with code and resource shrinking enabled for release builds. It uses a simple built-in layout to keep size small.

Android Kotlin

plugins {
    id 'com.android.application'
    id 'kotlin-android'
}

android {
    compileSdk 33

    defaultConfig {
        applicationId "com.example.appsize"
        minSdk 21
        targetSdk 33
        versionCode 1
        versionName "1.0"
    }

    buildTypes {
        release {
            minifyEnabled true
            shrinkResources true
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
}

// Simple MainActivity.kt
package com.example.appsize

import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(android.R.layout.simple_list_item_1)
    }
}

Important Notes

Always test your app after enabling shrinking to avoid removing needed code or resources.

Use ProGuard or R8 rules to keep important code from being removed.

Large images can be compressed or replaced with vector graphics to save space.

Summary

Enable minifyEnabled and shrinkResources in your build config to reduce app size.

Use ProGuard or R8 to remove unused code and rename classes.

Test your app carefully after optimization to ensure it still works well.