# Height and Width

Domains:

A component's height and width determine its size on the screen.

## Fixed Dimensions

The simplest way to set the dimensions of a component is by adding a fixed width and height to style. All dimensions in React Native are unitless, and represent density-independent pixels.

	import React, { Component } from 'react';
import { AppRegistry, View } from 'react-native';

export default class FixedDimensionsBasics extends Component {
render() {
return (
<View>
<View style={{width: 50, height: 50, backgroundColor: 'powderblue'}} />
<View style={{width: 100, height: 100, backgroundColor: 'skyblue'}} />
<View style={{width: 150, height: 150, backgroundColor: 'steelblue'}} />
</View>
);
}
}

// skip this line if using Create React Native App
AppRegistry.registerComponent('AwesomeProject', () => FixedDimensionsBasics);


Setting dimensions this way is common for components that should always render at exactly the same size, regardless of screen dimensions.

## Flex Dimensions

Use flex in a component's style to have the component expand and shrink dynamically based on available space. Normally you will use flex: 1, which tells a component to fill all available space, shared evenly amongst each other component with the same parent. The larger the flex given, the higher the ratio of space a component will take compared to its siblings.

A component can only expand to fill available space if its parent has dimensions greater than 0. If a parent does not have either a fixed width and height or flex, the parent will have dimensions of 0 and the flex children will not be visible.

	import React, { Component } from 'react';
import { AppRegistry, View } from 'react-native';

export default class FlexDimensionsBasics extends Component {
render() {
return (
// Try removing the flex: 1 on the parent View.
// The parent will not have dimensions, so the children can't expand.
// What if you add height: 300 instead of flex: 1?
<View style={{flex: 1}}>
<View style={{flex: 1, backgroundColor: 'powderblue'}} />
<View style={{flex: 2, backgroundColor: 'skyblue'}} />
<View style={{flex: 3, backgroundColor: 'steelblue'}} />
</View>
);
}
}

// skip this line if using Create React Native App
AppRegistry.registerComponent('AwesomeProject', () => FlexDimensionsBasics);


After you can control a component's size, the next step is to learn how to lay it out on the screen.

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