Custom fonts in Flutter

Introduction

Custom fonts let you use your favorite text styles in your app. This makes your app look unique and match your brand or style.

You want your app to have a special look with unique text styles.

You need to use a font that matches your company logo or design.

You want to improve readability with a font that suits your content.

You want to support different languages with specific fonts.

You want to make your app stand out from others with custom typography.

Syntax

Flutter

1. Add font files (e.g., .ttf) to your project folder, usually under assets/fonts.
2. Update pubspec.yaml to include the font:

flutter:
  fonts:
    - family: YourFontName
      fonts:
        - asset: assets/fonts/YourFontFile.ttf

3. Use the font in your app:

Text('Hello', style: TextStyle(fontFamily: 'YourFontName'))

The font family name in pubspec.yaml is what you use in your TextStyle.

Make sure to run flutter pub get after editing pubspec.yaml.

Examples

This example adds the Roboto font from the assets folder.

Flutter

flutter:
  fonts:
    - family: Roboto
      fonts:
        - asset: assets/fonts/Roboto-Regular.ttf

This uses the Roboto font for the text.

Flutter

Text('Welcome', style: TextStyle(fontFamily: 'Roboto'))

This example adds OpenSans font with regular and bold weights.

Flutter

flutter:
  fonts:
    - family: OpenSans
      fonts:
        - asset: assets/fonts/OpenSans-Regular.ttf
        - asset: assets/fonts/OpenSans-Bold.ttf
          weight: 700

This uses the bold weight of OpenSans font.

Flutter

Text('Bold Text', style: TextStyle(fontFamily: 'OpenSans', fontWeight: FontWeight.bold))

Sample App

This app shows text using the custom font named 'Lobster'. You need to add the Lobster font file to assets/fonts and declare it in pubspec.yaml before running.

Flutter

import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Custom Font Demo',
      home: Scaffold(
        appBar: AppBar(title: const Text('Custom Font Example')),
        body: const Center(
          child: Text(
            'Hello with Custom Font!',
            style: TextStyle(fontFamily: 'Lobster', fontSize: 24),
          ),
        ),
      ),
    );
  }
}

Important Notes

Always check the font license before using it in your app.

If the font does not show, check the pubspec.yaml indentation and asset paths carefully.

You can add multiple fonts and weights for more style options.

Summary

Custom fonts make your app text unique and stylish.

Add font files to assets and declare them in pubspec.yaml.

Use the font family name in TextStyle to apply the font.

Practice

1. What is the first step to use a custom font in a Flutter app?

easy

A. Add the font files to the assets folder and declare them in pubspec.yaml

B. Write the font name directly in the Text widget

C. Import a font package from pub.dev

D. Use the default system font without changes

Solution

1. Step 1: Add font files to assets

   You must first place your font files (like .ttf) inside an assets folder in your project.

2. Step 2: Declare fonts in pubspec.yaml

   Next, you declare these font files under the fonts section in pubspec.yaml so Flutter knows about them.

3. Final Answer:

   Add the font files to the assets folder and declare them in pubspec.yaml -> Option A

4. Quick Check:

   Custom fonts start with assets + pubspec.yaml declaration [OK]

Hint: Always start by adding font files and declaring in pubspec.yaml [OK]

Common Mistakes:

• Skipping pubspec.yaml declaration
• Trying to use font without adding files
• Using font name without quotes in TextStyle

2. Which of the following is the correct way to specify a custom font family in a Text widget's style?

easy

A. Text('Hello', style: TextStyle(fontStyle: 'MyFont'))

B. Text('Hello', style: TextStyle(font: 'MyFont'))

C. Text('Hello', style: TextStyle(fontName: 'MyFont'))

D. Text('Hello', style: TextStyle(fontFamily: 'MyFont'))

Solution

1. Step 1: Use fontFamily property in TextStyle

   The correct property to set a font family is fontFamily, not font, fontName, or fontStyle.

2. Step 2: Apply fontFamily in Text widget

   Use TextStyle(fontFamily: 'YourFontName') inside the style parameter of Text widget.

3. Final Answer:

   Text('Hello', style: TextStyle(fontFamily: 'MyFont')) -> Option D

4. Quick Check:

   fontFamily property sets custom font [OK]

Hint: Use fontFamily property inside TextStyle for custom fonts [OK]

Common Mistakes:

• Using font instead of fontFamily
• Confusing fontStyle with fontFamily
• Omitting quotes around font family name

3. Given this pubspec.yaml snippet:

fonts:
  - family: CoolFont
    fonts:
      - asset: assets/fonts/CoolFont-Regular.ttf
      - asset: assets/fonts/CoolFont-Bold.ttf
        weight: 700

What will this code display?

Text('Hi', style: TextStyle(fontFamily: 'CoolFont', fontWeight: FontWeight.bold))

medium

A. Text 'Hi' in CoolFont Bold style

B. Text 'Hi' in default font because fontWeight is ignored

C. Error because fontWeight 700 is invalid

D. Text 'Hi' in CoolFont Regular style ignoring bold

Solution

1. Step 1: Understand fontWeight mapping

   The pubspec.yaml declares two font assets: Regular (default weight) and Bold (weight 700).

2. Step 2: TextStyle uses fontWeight.bold

   Using fontWeight: FontWeight.bold matches weight 700, so Flutter uses the Bold font file.

3. Final Answer:

   Text 'Hi' in CoolFont Bold style -> Option A

4. Quick Check:

   fontWeight matches declared font weight for bold [OK]

Hint: Match fontWeight in TextStyle to declared font weights in pubspec.yaml [OK]

Common Mistakes:

• Ignoring fontWeight and expecting bold
• Assuming fontWeight 700 is invalid
• Not declaring font weights in pubspec.yaml

4. Why does this Flutter app fail to apply the custom font?

pubspec.yaml:
fonts:
  - family: FancyFont
    fonts:
      - asset: assets/fonts/FancyFont.ttf

Dart code:
Text('Hello', style: TextStyle(fontFamily: 'FancyFontt'))

medium

A. pubspec.yaml syntax error due to missing indentation

B. Font file is missing from assets folder

C. Font family name in TextStyle does not match pubspec.yaml

D. Text widget cannot use custom fonts

Solution

1. Step 1: Check fontFamily spelling in Dart code

   The Dart code uses 'FancyFontt' but pubspec.yaml declares 'FancyFont' (extra 't').

2. Step 2: Font family names must match exactly

   Font family names are case-sensitive and must match exactly between pubspec.yaml and Dart code.

3. Final Answer:

   Font family name in TextStyle does not match pubspec.yaml -> Option C

4. Quick Check:

   Font family names must match exactly [OK]

Hint: Check spelling of fontFamily matches pubspec.yaml exactly [OK]

Common Mistakes:

• Typos in font family names
• Forgetting to run flutter pub get after changes
• Incorrect indentation in pubspec.yaml

5. You want to use two different custom fonts in your Flutter app: 'Lobster' for titles and 'OpenSans' for body text. How should you organize your pubspec.yaml and Dart code to achieve this?

hard

A. Add both font files but use only one family name in pubspec.yaml

B. Declare both fonts under fonts in pubspec.yaml with different family names, then use fontFamily: 'Lobster' or 'OpenSans' in TextStyle accordingly

C. Declare only one font in pubspec.yaml and switch fontFamily names in Dart code

D. Use system fonts for titles and custom font for body text without declaring both

Solution

1. Step 1: Declare each font family separately in pubspec.yaml

   You must list each font family with its own name and font files under the fonts section.

2. Step 2: Use fontFamily property in Dart code for each Text widget

   Apply fontFamily: 'Lobster' for titles and fontFamily: 'OpenSans' for body text in TextStyle.

3. Final Answer:

   Declare both fonts under fonts in pubspec.yaml with different family names, then use fontFamily: 'Lobster' or 'OpenSans' in TextStyle accordingly -> Option B

4. Quick Check:

   Multiple fonts need separate declarations and usage [OK]

Hint: Declare each font family separately and use fontFamily accordingly [OK]

Common Mistakes:

• Declaring only one font family for multiple fonts
• Using wrong fontFamily names in Dart code
• Not adding all font files to assets