Minimizing bundle size

Learn more about the tools you can leverage to reduce the bundle size.

Bundle size matters

Material UI's maintainers take bundle size very seriously. Size snapshots are taken on every commit for every package and critical parts of those packages. Combined with dangerJS we can inspect detailed bundle size changes on every Pull Request.

When and how to use tree-shaking?

Tree-shaking Material UI works out of the box in modern frameworks. Material UI exposes its full API on the top-level @mui imports. If you're using ES6 modules and a bundler that supports tree-shaking (webpack >= 2.x, parcel with a flag) you can safely use named imports and still get an optimized bundle size automatically:

import { Button, TextField } from '@mui/material';

Development environment

Development bundles can contain the full library which can lead to slower startup times. This is especially noticeable if you use named imports from @mui/icons-material, which can be up to six times slower than the default import. For example, between the following two imports, the first (named) can be significantly slower than the second (default):

// 🐌 Named
import { Delete } from '@mui/icons-material';

// 🚀 Default
import Delete from '@mui/icons-material/Delete';

If this is an issue for you, you have two options:

Option one: use path imports

You can use path imports to avoid pulling in unused modules. For instance, use:

// 🚀 Fast
import Button from '@mui/material/Button';
import TextField from '@mui/material/TextField';

instead of top-level imports (without a Babel plugin):

import { Button, TextField } from '@mui/material';

This is the option we document in all the demos since it requires no configuration. It is encouraged for library authors that are extending the components. Head to Option 2 for the approach that yields the best DX and UX.

While importing directly in this manner doesn't use the exports in the main file of @mui/material, this file can serve as a handy reference as to which modules are public.

Be aware that we only support first and second-level imports. Anything deeper is considered private and can cause issues, such as module duplication in your bundle.

// ✅ OK
import { Add as AddIcon } from '@mui/icons-material';
import { Tabs } from '@mui/material';
//                         ^^^^^^^^ 1st or top-level

// ✅ OK
import AddIcon from '@mui/icons-material/Add';
import Tabs from '@mui/material/Tabs';
//                              ^^^^ 2nd level

// ❌ NOT OK
import TabIndicator from '@mui/material/Tabs/TabIndicator';
//                                           ^^^^^^^^^^^^ 3rd level

If you're using ESLint you can catch problematic imports with the no-restricted-imports rule. The following .eslintrc configuration will highlight problematic imports from @mui packages:

{
  "rules": {
    "no-restricted-imports": [
      "error",
      {
        "patterns": ["@mui/*/*/*"]
      }
    ]
  }
}

Option two: use a Babel plugin

This option provides the best user experience and developer experience:

UX: The Babel plugin enables top-level tree-shaking even if your bundler doesn't support it.
DX: The Babel plugin makes startup time in dev mode as fast as Option 1.
DX: This syntax reduces the duplication of code, requiring only a single import for multiple modules. Overall, the code is easier to read, and you are less likely to make a mistake when importing a new module.

import { Button, TextField } from '@mui/material';

However, you need to apply the two following steps correctly.

1. Configure Babel

Pick one of the following plugins:

babel-plugin-import with the following configuration:

yarn add -D babel-plugin-import

Create a .babelrc.js file in the root directory of your project:

const plugins = [
  [
    'babel-plugin-import',
    {
      libraryName: '@mui/material',
      libraryDirectory: '',
      camel2DashComponentName: false,
    },
    'core',
  ],
  [
    'babel-plugin-import',
    {
      libraryName: '@mui/icons-material',
      libraryDirectory: '',
      camel2DashComponentName: false,
    },
    'icons',
  ],
];

module.exports = { plugins };

babel-plugin-direct-import with the following configuration:

yarn add -D babel-plugin-direct-import

Create a .babelrc.js file in the root directory of your project:

const plugins = [
  [
    'babel-plugin-direct-import',
    { modules: ['@mui/material', '@mui/icons-material'] },
  ],
];

module.exports = { plugins };

If you are using Create React App, you will need to use a couple of projects that let you use .babelrc configuration, without ejecting.

yarn add -D react-app-rewired customize-cra

Create a config-overrides.js file in the root directory:

/* config-overrides.js */
/* eslint-disable react-hooks/rules-of-hooks */
const { useBabelRc, override } = require('customize-cra');

module.exports = override(useBabelRc());

If you wish, babel-plugin-import can be configured through config-overrides.js instead of .babelrc by using this configuration.

Modify your package.json commands:

   "scripts": {
-    "start": "react-scripts start",
-    "build": "react-scripts build",
-    "test": "react-scripts test",
+    "start": "react-app-rewired start",
+    "build": "react-app-rewired build",
+    "test": "react-app-rewired test",
     "eject": "react-scripts eject"
  }

Enjoy significantly faster start times.

2. Convert all your imports

Finally, you can convert your existing codebase to this option with this top-level-imports codemod. It will perform the following diffs:

-import Button from '@mui/material/Button';
-import TextField from '@mui/material/TextField';
+import { Button, TextField } from '@mui/material';

Available bundles

Default bundle

The packages published on npm are transpiled with Babel, optimized for performance with the supported platforms.

Custom bundles are also available:

Modern bundle
Legacy bundle

How to use custom bundles?

You are strongly discouraged to:

Import from any of the custom bundles directly. Do not do this:
```
import { Button } from '@mui/material/legacy';
```
You have no guarantee that the dependencies also use legacy or modern bundles, leading to module duplication in your JavaScript files.
Import from any of the undocumented files or folders. Do not do this:
```
import { Button } from '@mui/material/esm';
```
You have no guarantee that these imports will continue to work from one version to the next.

A great way to use these bundles is to configure bundler aliases, for example with Webpack's resolve.alias:

{
  resolve: {
    alias: {
      '@mui/material': '@mui/material/legacy',
      '@mui/styled-engine': '@mui/styled-engine/legacy',
      '@mui/system': '@mui/system/legacy',
      '@mui/base': '@mui/base/legacy',
      '@mui/utils': '@mui/utils/legacy',
      '@mui/lab': '@mui/lab/legacy',
    }
  }
}

Modern bundle

The modern bundle can be found under the /modern folder. It targets the latest released versions of evergreen browsers (Chrome, Firefox, Safari, Edge). This can be used to make separate bundles targeting different browsers.

Legacy bundle

If you need to support IE 11 you cannot use the default or modern bundle without transpilation. However, you can use the legacy bundle found under the /legacy folder. You don't need any additional polyfills.