Edit

useWindowDimensions

import { useWindowDimensions } from 'react-native';

useWindowDimensions automatically updates width and height values when screen size changes. You can get your application window's width and height like so:

const windowWidth = useWindowDimensions().width;
const windowHeight = useWindowDimensions().height;

Example

import React from "react";
import { View, StyleSheet, Text, useWindowDimensions } from "react-native";

export default function App() {
  const window = useWindowDimensions();
  return (
    <View style={styles.container}>
      <Text>{`Window Dimensions: height - ${window.height}, width - ${window.width}`}</Text>
    </View>
  );
}
const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: "center",
    alignItems: "center"
  }
});

• The useDimensions hook from the community React native hooks library aims to make handling screen/window size changes easier to work with.
• React Native Responsive Dimensions also comes with responsive hooks.

Properties

fontScale

The scale of the font currently used. Some operating systems allow users to scale their font sizes larger or smaller for reading comfort. This property will let you know what is in effect.

useWindowDimensions().fontScale;

height

The height in pixels of the window or screen your app occupies.

useWindowDimensions().height;

scale

The ]pixel ratio of the device your app is running on.

useWindowDimensions().scale;

A value of 1 indicates PPI/DPI of 96 (76 on some platforms). 2 indicates a Retina or high DPI display.

width

The width in pixels of the window or screen your app occupies.

useWindowDimensions().width;