---
id: style-fonts
title: Changing fonts
sidebar_label: Changing fonts
---

Before you begin using your own fonts, you'll first need to add them to the app project.

* **Android** - add the `.ttf` or `.otf` files to `src/main/assets/fonts/`
* **iOS** - follow this [guide](https://medium.com/react-native-training/react-native-custom-fonts-ccc9aacf9e5e)

Once we've added the font files to our project, we can star using them in options.

:::note
When declaring fonts in options, use only the file name without the file type suffix.
:::

## BottomTab font

```js
options: {
  bottomTab: {
    fontFamily: 'helvetica'
  }
}
```

## Button font

```js
options: {
  rightButtons: [
    {
      id: 'SAVE_BUTTON',
      text: 'Save',
      fontFamily: 'helvetica'
    }
  ],
  leftButtons: [
    {
      id: 'CANCEL_BUTTON',
      text: 'Cancel',
      fontFamily: 'helvetica'
    }
  ]
}
```

## Title font

```js
options: {
  topBar: {
    title: {
      fontFamily: 'helvetica'
    }
  }
}
```

## Subtitle font

```js
options: {
  topBar: {
    subtitle: {
      fontFamily: 'helvetica'
    }
  }
}
```

## Back button

In iOS the back button will display the title of the previous screen. Use the `backButton` option to modify its font family.

```js
options: {
  topBar: {
    backButton: {
      fontFamily: 'helvetica'
    }
  }
}
```