react native asign width to image

1import { Dimensions } from "react-native";
2const win = Dimensions.get('window');
3
4<Image
5  style={{
6    width: win.width/2,
7    height: win.width/2,
8    resizeMode: "contain",
9    alignSelf: "center",
10    borderWidth: 1,
11    borderRadius: 20,
12  }}
13  source={{uri:'https://facebook.github.io/react/img/logo_og.png'}}
14  resizeMode="stretch"
15/>

1First import Dimensions from react-native
2
3import { Dimensions } from 'react-native';
4then you have to get the dimensions of the window
5
6const win = Dimensions.get('window');
7Now calculate ratio as
8
9const ratio = win.width/541; //541 is actual image width
10now the add style to your image as
11
12imageStyle: {
13    width: win.width,
14    height: 362 * ratio, //362 is actual height of image
15}