How to Make a Flutter App Responsive for Different Mobile Screen Sizes? - Stack Overflow

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I am working on a Flutter app where I need to make the UI responsive for different mobile screen sizes. The design is provided in Figma, where we have specific pixel values for height, width, and text sizes. However, since Flutter uses logical pixels and mobile app run on physical pixels, I am facing issues when adapting the design to smaller screens.

Issue: The UI looks identical on both small and large mobile screens instead of adjusting proportionally.

I tried using the flutter_screenutil package, but elements like TextField remain the same size across different mobile devices, which makes the design inconsistent.

What I Want to Achieve: The UI should automatically scale and adjust based on the mobile screen size (without affecting the layout).

Text, buttons, and other widgets should proportionally adapt to both small and large mobile screens.

What I Have Tried: Used flutter_screenutil for scaling, but it doesn't seem to adjust text fields properly on smaller screens.

Manually setting different values for different devices, but that’s not an efficient approach.

Question: What is the best approach to make a Flutter app fully responsive for all mobile devices while following a Figma design that provides fixed pixel values? Are there any recommended packages or best practices that can help achieve this without breaking the design consistency?

Any guidance or code examples would be greatly appreciated!

I am working on a Flutter app where I need to make the UI responsive for different mobile screen sizes. The design is provided in Figma, where we have specific pixel values for height, width, and text sizes. However, since Flutter uses logical pixels and mobile app run on physical pixels, I am facing issues when adapting the design to smaller screens.

Issue: The UI looks identical on both small and large mobile screens instead of adjusting proportionally.

I tried using the flutter_screenutil package, but elements like TextField remain the same size across different mobile devices, which makes the design inconsistent.

What I Want to Achieve: The UI should automatically scale and adjust based on the mobile screen size (without affecting the layout).

Text, buttons, and other widgets should proportionally adapt to both small and large mobile screens.

What I Have Tried: Used flutter_screenutil for scaling, but it doesn't seem to adjust text fields properly on smaller screens.

Manually setting different values for different devices, but that’s not an efficient approach.

Question: What is the best approach to make a Flutter app fully responsive for all mobile devices while following a Figma design that provides fixed pixel values? Are there any recommended packages or best practices that can help achieve this without breaking the design consistency?

Any guidance or code examples would be greatly appreciated!

• flutter
• mobile-application

Share Improve this question Follow edited Mar 27 at 14:44 Vy Do 52.9k6969 gold badges256256 silver badges387387 bronze badges asked Mar 27 at 14:05 Ramesh RajaRamesh Raja 1111 bronze badge

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Adapting Figma designs with fixed pixel values to responsive Flutter UIs is a common challenge, especially given the difference between Figma's design pixels and Flutter's logical pixels (dp). You're right that sometimes flutter_screenutil, while powerful, might not seem to scale all elements as expected out-of-the-box, particularly widgets like TextField if not configured or used carefully. ** ** The core issue is that simply using the pixel values from Figma directly in Flutter (which uses logical pixels) won't automatically create proportional scaling across different screen sizes and aspect ratios. The goal is to scale your Figma dimensions proportionally based on the actual device screen size compared to the reference design size in Figma.

Here's the recommended approach, focusing on using flutter_screenutil correctly and supplementing it with Flutter's built-in layout widgets:

1. Configure flutter_screenutil Correctly (Crucial Step)

The most common reason flutter_screenutil might not work as expected is incorrect or late initialization, or not providing the correct design size.

Add flutter_screenutil to your pubspec.yaml and run flutter pub get.

Initialize Early and Correctly: Wrap your MaterialApp with ScreenUtilInit and provide the exact width and height used in your Figma design file as the designSize. This is the reference point for all scaling calculations. Initialize it in the builder of MaterialApp.

import 'package:flutter/material.dart';
import 'package:flutter_screenutil/flutter_screenutil.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  // --- DEFINE THE FIGMA DESIGN SIZE HERE ---
  // Example: iPhone 11 Pro / X dimensions commonly used in Figma
  static const double designScreenWidth = 375;
  static const double designScreenHeight = 812;

  @override
  Widget build(BuildContext context) {
    // Use ScreenUtilInit in the builder of MaterialApp
    return ScreenUtilInit(
      designSize: const Size(designScreenWidth, designScreenHeight),
      minTextAdapt: true, // Adapt text size to prevent overflow
      splitScreenMode: true, // Support split screen (optional)
      builder: (context, child) {
        return MaterialApp(
          debugShowCheckedModeBanner: false,
          title: 'Responsive Flutter App',
          theme: ThemeData(
            primarySwatch: Colors.blue,
            // Optionally define base text styles using .sp here
            // textTheme: TextTheme(
            //   bodyMedium: TextStyle(fontSize: 14.sp),
            // ),
          ),
          home: child, // Pass the child received from builder
        );
      },
      // Provide your main page (or router) as the child of ScreenUtilInit
      child: const HomePage(),
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({super.key});
  // ... rest of your page code
}

2. Consistently Use flutter_screenutil Extensions

Once initialized, use the provided extensions for all size-related values you get from Figma:

**.w: For width values (e.g., SizedBox(width: 100.w)).

.h: For height values (e.g., Container(height: 50.h)).

.sp: For font sizes (e.g., Text('Hello', style: TextStyle(fontSize: 16.sp))). This often scales slightly differently than .w/.h to maintain readability (minTextAdapt: true affects this).

.r: For radius values (e.g., BorderRadius.circular(12.r)). It often scales based on the smaller of width/height ratio.

For Padding/Margin: Use EdgeInsets.symmetric(horizontal: 16.w, vertical: 8.h) or EdgeInsets.fromLTRB(10.w, 5.h, 10.w, 5.h).**

Example Usage:

import 'package:flutter/material.dart';
import 'package.flutter_screenutil/flutter_screenutil.dart';

class HomePage extends StatelessWidget {
  const HomePage({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(
          'Responsive Demo',
          style: TextStyle(fontSize: 18.sp), // Use .sp
        ),
      ),
      body: Padding(
        padding: EdgeInsets.symmetric(horizontal: 20.w, vertical: 15.h), // Use .w, .h
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: [
            Container(
              width: 300.w,  // Use .w
              height: 150.h, // Use .h
              decoration: BoxDecoration(
                color: Colors.blueAccent,
                borderRadius: BorderRadius.circular(12.r), // Use .r
              ),
              alignment: Alignment.center,
              child: Text(
                'Scaled Container',
                style: TextStyle(fontSize: 16.sp, color: Colors.white), // Use .sp
              ),
            ),
            SizedBox(height: 20.h), // Use .h for spacing

            // --- Fixing the TextField Scaling Issue ---
            TextField(
              style: TextStyle(fontSize: 14.sp), // Scale inner font size
              decoration: InputDecoration(
                hintText: 'Enter text here...',
                hintStyle: TextStyle(fontSize: 14.sp, color: Colors.grey), // Scale hint font size
                // IMPORTANT: Scale content padding for intrinsic height
                contentPadding: EdgeInsets.symmetric(
                  horizontal: 12.w,
                  vertical: 10.h, // Adjust vertical padding too!
                ),
                border: OutlineInputBorder(
                  borderRadius: BorderRadius.circular(8.r), // Scale border radius
                  borderSide: BorderSide(
                    color: Colors.grey,
                    width: 1.w, // Scale border width
                  ),
                ),
                // If you have icons, scale their size too
                // prefixIcon: Icon(Icons.person, size: 20.sp),
              ),
            ),
            SizedBox(height: 20.h),

            ElevatedButton(
              onPressed: () {},
              style: ElevatedButton.styleFrom(
                // Scale button padding
                padding: EdgeInsets.symmetric(horizontal: 24.w, vertical: 12.h),
                textStyle: TextStyle(fontSize: 16.sp), // Scale button text font size
                shape: RoundedRectangleBorder(
                  borderRadius: BorderRadius.circular(8.r), // Scale button border radius
                ),
              ),
              child: const Text('Scaled Button'),
            ),
          ],
        ),
      ),
    );
  }
}

3. Addressing the TextField Specific Issue

TextField often doesn't scale "automatically" just by placing it in a scaled container because its intrinsic height depends heavily on its InputDecoration, specifically:

contentPadding: This is the internal padding within the text field. If you don't scale this using .w and .h, the field's height won't adapt correctly. This is often the missing piece.

fontSize: Both the main style's fontSize and the hintStyle's fontSize need to be scaled using .sp.

Icons/Borders: If you have icons (prefixIcon, suffixIcon), scale their size. Scale borderRadius and borderSide.width in the border property.

By applying .sp, .w, .h, and .r to these internal properties of the TextField's decoration and style, it will scale proportionally along with other elements.

4. Complement with Flutter's Layout Widgets

Don't rely solely on fixed, scaled pixel values for everything. Use Flutter's powerful layout widgets for structure and flexibility:

Expanded & Flexible: Use inside Row and Column to make widgets share available space proportionally. This naturally adapts to different screen widths/heights.

Row(
  children: [
    Expanded(flex: 2, child: Container(/* ... */)),
    SizedBox(width: 8.w), // Scaled gap
    Expanded(flex: 1, child: Container(/* ... */)),
  ],
)

LayoutBuilder: Build different widget trees based on the constraints (available space) provided by the parent widget. Useful for more complex adaptive layouts.

FractionallySizedBox: Size a child as a fraction (percentage) of the available space.

I hope this information will be useful for you.

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