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Easily make an element as wide or as tall (relative to its parent) with the width and height utilities.

Supported values

The sizing properties: width, height, minHeight, maxHeight, minWidth, and maxWidth are using the following custom transform function for the value:

function transform(value) {
  return value <= 1 ? `${value * 100}%` : value;

If the value is between [0, 1], it's converted to percent. Otherwise, it is directly set on the CSS property.

Width 1/4
Width 300
Width 75%
Width 1
<Box sx={{ width: 1/4 }}> // Equivalent to width: '25%'
<Box sx={{ width: 300 }}> // Numbers are converted to pixel values.
<Box sx={{ width: '75%' }}> // String values are used as raw CSS.
<Box sx={{ width: 1 }}> // 100%


Width 25%
Width 50%
Width 75%
Width 100%
Width auto
<Box sx={{ width: '25%' }}><Box sx={{ width: '50%' }}><Box sx={{ width: '75%' }}><Box sx={{ width: '100%' }}><Box sx={{ width: 'auto' }}>


The max-width property allows setting a constraint on your breakpoints. In this example, the value resolves to

<Box sx={{ maxWidth: 'md' }}>


Height 25%
Height 50%
Height 75%
Height 100%
<Box sx={{ height: '25%' }}><Box sx={{ height: '50%' }}><Box sx={{ height: '75%' }}><Box sx={{ height: '100%' }}>


import { sizing } from '@mui/system';
Import name Prop CSS property Theme key
width width width none
maxWidth maxWidth max-width theme.breakpoints.values
minWidth minWidth min-width none
height height height none
maxHeight maxHeight max-height none
minHeight minHeight min-height none
boxSizing boxSizing box-sizing none