Font

expo-font allows loading fonts from the web and using them in React Native components. See more detailed usage information in the Fonts guide.

Platform Compatibility

Android Device	Android Emulator	iOS Device	iOS Simulator	Web

Installation

Terminal

→ expo install expo-font

If you're installing this in a bare React Native app, you should also follow these additional installation instructions.

Usage

Example: hook

import * as React from 'react';
import { View, Text, StyleSheet } from 'react-native';
import { useFonts } from 'expo-font';

export default function App() {
  const [loaded] = useFonts({
    Montserrat: require('./assets/fonts/Montserrat.ttf'),
  });
  
  if (!loaded) {
    return null;
  }

  return (
    <View style={styles.container}>
      <Text style={{ fontFamily: 'Montserrat', fontSize: 30 }}>Montserrat</Text>
    </View>
  );
}

%%placeholder-start%%const styles = StyleSheet.create({ ... }); %%placeholder-end%%const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: '#fff',
    alignItems: 'center',
    justifyContent: 'center',
  },
});

Example: functions

import * as React from 'react';
import { Text, View, StyleSheet } from 'react-native';
import * as Font from 'expo-font';

export default class App extends React.Component {
  state = {
    fontsLoaded: false,
  };

  async loadFonts() {
    await Font.loadAsync({
      // Load a font `Montserrat` from a static resource
      Montserrat: require('./assets/fonts/Montserrat.ttf'),

      // Any string can be used as the fontFamily name. Here we use an object to provide more control
      'Montserrat-SemiBold': {
        uri: require('./assets/fonts/Montserrat-SemiBold.ttf'),
        display: Font.FontDisplay.FALLBACK,
      },
    });
    this.setState({ fontsLoaded: true });
  }

  componentDidMount() {
    this.loadFonts();
  }

  render() {
    // Use the font with the fontFamily property after loading
    if (this.state.fontsLoaded) {
      return (
        <View style={styles.container}>
          <Text style={{ fontSize: 20 }}>Default Font</Text>
          <Text style={{ fontFamily: 'Montserrat', fontSize: 20 }}>Montserrat</Text>
          <Text style={{ fontFamily: 'Montserrat-SemiBold', fontSize: 20 }}>
            Montserrat-SemiBold
          </Text>
        </View>
      );
    } else {
      return null;
    }
  }
}

%%placeholder-start%%const styles = StyleSheet.create({ ... }); %%placeholder-end%%const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: '#fff',
    alignItems: 'center',
    justifyContent: 'center',
  },
});

API

import * as Font from 'expo-font';

Hooks

`useFonts`

Arguments

map (string | Record<string, FontSource>) - A map of fontFamilys to FontSources. After loading the font you can use the key in the fontFamily style prop of a Text element.

const [loaded, error] = useFonts({ ... });

Load a map of fonts with loadAsync. This returns a boolean if the fonts are loaded and ready to use. It also returns an error if something went wrong, to use in development.

Note, the fonts are not "reloaded" when you dynamically change the font map.

Returns

[boolean, Error | null]

loaded (boolean) - A boolean to detect if the font for fontFamily has finished loading.
error (Error | null) - An error encountered when loading the fonts.

Methods

`isLoaded(fontFamily)`

Arguments

fontFamily (string) - The name used to load the FontResource.

Synchronously detect if the font for fontFamily has finished loading.

Returns

boolean

Returns true if the font has fully loaded.

`isLoading(fontFamily)`

Arguments

fontFamily (string) - The name used to load the FontResource.

Synchronously detect if the font for fontFamily is still being loaded.

Returns

boolean

Returns true if the font is still loading.

`loadAsync(fontFamilyOrFontMap, source)`

Arguments

fontFamilyOrFontMap (string | Record<string, FontSource>) - string or map of values that can be used as the fontFamily style prop with React Native Text elements.
source? (FontSource) - the font asset that should be loaded into the fontFamily namespace.

Highly efficient method for loading fonts from static or remote resources which can then be used with the platform's native text elements. In the browser this generates a @font-face block in a shared style sheet for fonts. No CSS is needed to use this method.

Returns

Promise<void>

Returns a promise that fulfils when the font has loaded. Often you may want to wrap the method in a try/catch/finally to ensure the app continues if the font fails to load.

`processFontFamily(fontFamily)`

Arguments

fontFamily (null | string) - Name of font to process.

Used to transform font family names to the scoped name. This does not need to be called in standalone or bare apps but it will return unscoped font family names if it is called in those contexts.

Returns

string | null

Returns a name processed for use with the current workflow.

`unloadAllAsync()`

Unloads all the custom fonts. This is used for testing.

Returns

Promise<void>

`unloadAsync(fontFamilyOrFontMap, options)`

Arguments

fontFamilyOrFontMap (string | Record<string, UnloadFontOptions>) - The name or names of the custom fonts that will be unloaded.
options? (UnloadFontOptions) - When fontFamilyOrFontMap is a string, this should be the font source used to load the custom font originally.

Unload custom fonts matching the fontFamilys and display values provided. Because fonts are automatically unloaded on every platform this is mostly used for testing.

Returns

Promise<void>

Types

`FontResource`

An object used to dictate the resource that is loaded into the provided font namespace when used with loadAsync.

Name	Type	Description
display (optional)	`FontDisplay`	Web Only. Sets the `font-display` property for a given typeface in the browser.
uri	`string \| number`	-

`FontSource`

The different types of assets you can provide to the loadAsync() function. A font source can be a URI, a module ID, or an Expo Asset.

Acceptable values are: string, number, Asset, FontResource.

`UnloadFontOptions`

Pick<FontResource, 'display'>

Object used to query fonts for unloading.

Enums

`FontDisplay`

Web Only. Sets the font-display for a given typeface. The default font value on web is FontDisplay.AUTO. Even though setting the fontDisplay does nothing on native platforms, the default behavior emulates FontDisplay.SWAP on flagship devices like iOS, Samsung, Pixel, etc. Default functionality varies on One Plus devices. In the browser this value is set in the generated @font-face CSS block and not as a style property meaning you cannot dynamically change this value based on the element it's used in.

AUTO - (Default) The font display strategy is defined by the user agent or platform. This generally defaults to the text being invisible until the font is loaded. Good for buttons or banners that require a specific treatment.
FontDisplay.AUTO ＝ "auto"
BLOCK - The text will be invisible until the font has loaded. If the font fails to load then nothing will appear - it's best to turn this off when debugging missing text.
FontDisplay.BLOCK ＝ "block"
FALLBACK - Splits the behavior between SWAP and BLOCK. There will be a 100ms timeout where the text with a custom font is invisible, after that the text will either swap to the styled text or it'll show the unstyled text and continue to load the custom font. This is good for buttons that need a custom font but should also be quickly available to screen-readers.
FontDisplay.FALLBACK ＝ "fallback"
OPTIONAL - This works almost identically to FALLBACK, the only difference is that the browser will decide to load the font based on slow connection speed or critical resource demand.
FontDisplay.OPTIONAL ＝ "optional"
SWAP - Fallback text is rendered immediately with a default font while the desired font is loaded. This is good for making the content appear to load instantly and is usually preferred.
FontDisplay.SWAP ＝ "swap"

Error Codes

Code	Description
ERR_FONT_API	If the arguments passed to `loadAsync` are invalid.
ERR_FONT_SOURCE	The provided resource was of an incorrect type.
ERR_WEB_ENVIRONMENT	The browser's `document` element doesn't support injecting fonts.
ERR_DOWNLOAD	Failed to download the provided resource.
ERR_FONT_FAMILY	Invalid font family name was provided.
ERR_UNLOAD	Attempting to unload fonts that haven't finished loading yet.