How to Fix ‘A RenderFlex Overflowed by X Pixels’ – The Most Common Flutter Layout Error

Estimated reading time: 10 minutes

If you’ve been working with Flutter for even a short while, chances are you’ve seen this dreaded red-and-yellow warning: “A RenderFlex Overflowed by XX pixels.” It’s one of those common layout issues that almost every beginner runs into — and honestly, even experienced Flutter devs encounter it when moving fast.

This error pops up when your widgets don’t have enough room to fit within the given space. Think of it like trying to squeeze a long paragraph into a tiny text box — Flutter is just letting you know that something doesn’t fit properly.

In this guide, we’ll look at why this error happens, how to fix it step by step, and some simple best practices to help you avoid it in the future.

Overview

The RenderFlex overflow error occurs when the widgets inside a Row or Column take up more space than is available. Since Flutter can’t shrink them any further, it displays an overflow warning.

Common symptoms include:

• Yellow and black stripes appearing at the screen edges
• Error message like: A RenderFlex overflowed by 28 pixels on the right
• Often happens in Rows containing text or images
• Also happens in Columns when widgets are taller than the screen

Why It Happens

Here are some of the most frequent causes:

1. Hardcoded dimensions that don’t fit the screen size
2. Long text inside a Row without any flexible widgets
3. Too many children in a Column without scrolling enabled
4. Images that are too wide for their containers
5. Not using Expanded or Flexible where needed

How to Fix It (Step by Step)

1. Fix Overflow in a Row

If your Row has text or widgets that take too much space, wrap them with Expanded or Flexible to allow Flutter to manage sizing:

Row(
  children: [
    Icon(Icons.info),
    SizedBox(width: 10),
    Expanded(
      child: Text(
        'This is a long message that would normally overflow in a Row.',
        maxLines: 2,
        overflow: TextOverflow.ellipsis,
      ),
    ),
  ],
);
  

2. Fix Overflow in a Column

When a Column’s widgets exceed the screen height, wrap it in a SingleChildScrollView to make it scrollable.

SingleChildScrollView(
  child: Column(
    children: [
      Text('A very long column of texts...'),
      SizedBox(height: 20),
      ...List.generate(20, (i) => Text('Item $i')),
    ],
  ),
);
  

3. Use Flexible Layouts Instead of Fixed Sizes

Avoid setting fixed widths or heights unless absolutely necessary. Let Flutter handle the sizing automatically whenever possible.

4. Add SafeArea to Prevent System UI Overlaps

If your content is getting cut off at the top or bottom (because of notches or the system bar), use SafeArea to keep it visible.

SafeArea(
  child: Column(
    children: [
      Text('Content is now safely within visible area'),
    ],
  ),
);
  

5. Use Wrap Instead of Row for Many Children

If you’re displaying multiple chips, tags, or buttons in a Row, switch to Wrap so they automatically flow to the next line.

Wrap(
  spacing: 8,
  runSpacing: 8,
  children: [
    Chip(label: Text('Flutter')),
    Chip(label: Text('Dart')),
    Chip(label: Text('UI')),
    Chip(label: Text('Development')),
  ],
);
  

Best Practices

• Always test your UI on small screens or use Device Preview
• Use Expanded in Rows to share space evenly
• Use Flexible when you need partial control over space
• Wrap long content with scroll views
• Avoid fixed pixel values for responsive design

Pro Tips:

• If a Row overflows, try Expanded first.
• Prefer Wrap instead of Row for tags, chips, or dynamic lists.
• Use MediaQuery to make layouts responsive.
• Remember: overflow in a Column = use scroll; overflow in a Row = use flexible widgets.

Examples

Example 1: Fixing overflow in a pricing card layout:

Row(
  crossAxisAlignment: CrossAxisAlignment.start,
  children: [
    Text('\$999', style: TextStyle(fontSize: 28, fontWeight: FontWeight.bold)),
    SizedBox(width: 12),
    Expanded(
      child: Text(
        'Ultimate Pro Max Annual Subscription with extended features and priority support.',
        maxLines: 2,
        overflow: TextOverflow.ellipsis,
      ),
    ),
  ],
);
  

Example 2: Fixing overflow in a button row:

Row(
  children: [
    Expanded(child: ElevatedButton(onPressed: () {}, child: Text('Cancel'))),
    SizedBox(width: 10),
    Expanded(child: ElevatedButton(onPressed: () {}, child: Text('Confirm'))),
  ],
);
  

Conclusion

The “RenderFlex Overflowed” error can be annoying at first, but once you understand how Flutter’s layout system works, it’s easy to fix. Whether it’s a Row, Column, Wrap, or ScrollView issue, the key is to make your widgets adaptable instead of forcing fixed sizes.

Play around with Expanded, Flexible, Wrap, and SingleChildScrollView — these four widgets alone can prevent most overflow issues in Flutter layouts.

Now go ahead — fix that layout and make your UI rock-solid!

FAQ

1. Why does my Row overflow even with short text?

Because the Row’s children don’t know how to share available space. Using Expanded helps distribute it properly.

2. When should I use SingleChildScrollView?

Use it anytime your Column’s content is longer than the screen height.

3. Does overflow affect performance?

No, but it makes your UI look broken — so it’s best to fix it right away.

4. Should I avoid fixed heights?

Yes, especially in responsive designs. Flexible layouts are your friend.

5. Is Wrap slower than Row?

Not really. Wrap is ideal for dynamic or responsive lists of items like chips or buttons.