Flutter layout errorFlutter: “A RenderFlex overflowed by … pixels on the right” (or bottom)

Why the Row or Column overflows, and the fix

1. 01

   A child in a Row or Column has no size limit

   “The error often occurs when a Column or Row has a child widget that isn't constrained in its size.” Flutter, Common Flutter errors

   A Row does not limit the width of its children. A long Text, or a Column holding one, tries to be as wide as all its characters and pushes past the edge. The error names the overflowing widget and the file and line in your code.

2. 02

   Wrap the child in Expanded or Flexible

   “One way to do it is to wrap the Column in an Expanded widget” Flutter, Common Flutter errors

   Expanded makes the child take the space left in the Row, so the text wraps instead of overflowing. Flexible does the same but lets the child be smaller. Expanded is Flexible with a flex factor of 1.

   Row(
     children: [
       const Icon(Icons.message),
       Expanded(
         child: Column(
           crossAxisAlignment: CrossAxisAlignment.start,
           children: [Text(title), Text(longDescription)],
         ),
       ),
     ],
   )

3. 03

   Overflow at the bottom: the screen is too short

   A Column with a form or a long card list overflows at the bottom on small phones, or when the keyboard opens and takes half the screen. Wrap the content in SingleChildScrollView so it can scroll, or use a ListView. Use Expanded on the part that should grow, not on every child.

   Scaffold(
     body: SingleChildScrollView(
       child: Column(children: formFields),
     ),
   )

4. 04

   It looked fine on your phone

   “When it happens, yellow and black stripes appear, indicating the area of overflow in the app UI.” Flutter, Common Flutter errors

   Overflow depends on screen size and the user’s text size, so it slips through testing on one device. Run the app on a small simulator and with the largest accessibility text size before release. The stripes appear only in debug builds, so a release build gives no visual warning for the overflow.

Checked against the vendor’s docs on November 7, 2026: Flutter docs: Common Flutter errors (RenderFlex overflow).

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