How to Reduce Flutter App Size by 60% (Proven Optimization Tricks)

Introduction

Is your Flutter app bloated, slow to download, or failing Play Store size limits? You're not alone. Many developers struggle with oversized apps—hurting performance, increasing uninstall rates, and frustrating users with limited storage.

But what if you could shrink your Flutter app size by up to 60% without sacrificing features?

In this guide, you’ll learn how to reduce Flutter app size using proven, practical techniques. Whether you're preparing for production or optimizing an MVP, these tips will save space and improve performance.

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Why Flutter Apps Become Too Large

Before optimizing, it's important to understand what causes Flutter apps to grow beyond control:

• Use of unnecessary packages or libraries
• Assets (images, fonts, videos) not compressed
• Debug builds instead of release builds
• Unoptimized native code or architecture
• No use of code shrinking tools like ProGuard

Let’s dive into the solutions.

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1. Use Flutter’s  --split-per-abi  Flag

• What it does:

Generates separate APKs for different device architectures (ARM, ARM64, x86), rather than bundling all in one.

• How to use:

 flutter build apk --split-per-abi   

• Result:

Reduces app size significantly, especially on production builds. You can expect up to 30–40% savings just from this step.

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2. Build in Release Mode

Why it matters:

Debug builds are bloated with debugging tools and symbols.

Use this:

 flutter build apk --release 

Tip:

Always test your app in release mode before publishing to get accurate size estimates.

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3. Compress and Optimize Assets

Large images and unused fonts are hidden size culprits.

Do this:

• Use tools like TinyPNG or ImageOptim
• Convert PNGs to WebP where supported
• Avoid oversized resolutions for mobile
• Remove unused assets from  pubspec.yaml 

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4. Use Dart Obfuscation and Tree Shaking

• Tree Shaking:

Removes unused Dart code.

• Obfuscation:

Makes code harder to reverse engineer (and may reduce size).

• Build like this:

 flutter build apk --release --obfuscate   --split-debug-info=/<project-directory>/debug-info

Warning: Save the  debug-info  directory. You’ll need it to debug crashes in obfuscated builds.

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5. Remove Unused Packages

1. Why it's important:

Many packages include native code or bloated dependencies.

2. Best practices:

• Audit  pubspec.yaml  regularly
• Remove unused plugins (e.g., for unused Firebase features)
• Replace large packages with lightweight alternatives

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6. Enable ProGuard for Android

ProGuard helps shrink, obfuscate, and optimize your Android build.

How to enable:

In  android/app/build.gradle :

 minifyEnabled true

shrinkResources true

proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro' 

Note:

Make sure essential Flutter classes aren’t stripped out. Check ProGuard rules and test thoroughly.

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7. Avoid Using Heavy Plugins

Some plugins (especially related to camera, AR, maps, and analytics) pull in large native dependencies.

Tip:

• Use only essential plugins
• For analytics or crash reporting, opt for modular SDKs

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8. Use AAB (Android App Bundle) Instead of APK

Google Play recommends publishing with AABs for optimized delivery.

Use this:

 flutter build appbundle 

Benefit:

Google Play serves only the necessary code and resources per device, reducing the download size.

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FAQ: How to Reduce Flutter App Size

1. How can I check my Flutter app size?

Use:

 flutter build apk --analyze-size 

Then, view the report in the browser to inspect size breakdowns.

2. Does using Firebase increase Flutter app size?

Yes. Firebase plugins often include native SDKs. Only include what you need (e.g., avoid  firebase_analytics  if not required).

3. Can removing fonts help reduce Flutter app size?

Absolutely. Each custom font adds MBs, especially if multiple weights/styles are used. Stick to system fonts when possible.

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Conclusion

Flutter is powerful, but app size can quickly get out of hand without proper optimization. By using techniques like ABI splitting, asset compression, and ProGuard, you can reduce Flutter app size by up to 60%—delivering faster downloads, better performance, and happier users.

Which of these optimizations have you already tried?
Drop a comment or share your best tip for reducing Flutter app size!