RN responsive font sizes

fontUtils.js

import { Dimensions, Platform, PixelRatio } from 'react-native'

const { width: SCREEN_WIDTH } = Dimensions.get('window')

// based on iphone 5s's scale
const scale = SCREEN_WIDTH / 320

export function normaliseSize(size) {
  const newSize = size * scale
  if (Platform.OS === 'ios') {
    return Math.round(PixelRatio.roundToNearestPixel(newSize))
  }

  return Math.round(PixelRatio.roundToNearestPixel(newSize)) - 2
}