# The ThemeData.useMaterial3 flag is true by default

> The ThemeData.useMaterial3 flag is now set to true by default.




:::important
These breaking change docs are accurate, as of the release
under which they are published. Over time, the
workarounds described here might become inaccurate.
We don't, in general, keep these breaking change docs up
to date as of each release.

The [breaking change index file](/release/breaking-changes)
lists the docs created for each release.
:::


## Summary

The Material library has been updated to match
the latest Material Design spec.
Changes include new components, new component themes,
and updated component visuals.
As of this release, [`ThemeData.useMaterial3`][] is set `true` by default.

## Background

Flutter's Material widgets now fully support Material 3 and,
as of Flutter 3.16, Material 3 is now the default style.

The appearance of Material 3 components are primarily determined by
the values for [`ThemeData.colorScheme`][] and [`ThemeData.textTheme`][].
ColorScheme makes it easier to create dark and light schemes so that
your app is both aesthetically pleasing and
compliant with accessibility requirements.
To further customize the appearance of Material 3 components,
add component themes to your `ThemeData`,
such as [`ThemeData.segmentedButtonTheme`][] or [`ThemeData.snackBarTheme`][].

Additionally, Material 3 improves motion by using easing and duration tokens.
This means that Material 2 curves have been renamed to include
the word "legacy" and will eventually be deprecated and removed.

Check out the [Material 3 gallery][] to test out
all the new components and compare them with Material 2.

[`ThemeData.colorScheme`]: https://api.flutter.dev/flutter/material/ThemeData/colorScheme.html
[`ThemeData.textTheme`]: https://api.flutter.dev/flutter/material/ThemeData/textTheme.html
[`ThemeData.segmentedButtonTheme`]: https://api.flutter.dev/flutter/material/ThemeData/segmentedButtonTheme.html
[`ThemeData.snackBarTheme`]: https://api.flutter.dev/flutter/material/ThemeData/snackBarTheme.html

## Migration guide

Prior to the 3.16 release, the changes were "opt-in"
using the `useMaterial3` theme property on `ThemeData`.
As of this release, `useMaterial3` is `true` by default.
You can still opt out of the Material 3 version of the Material library by
specifying `useMaterial3: false` in your `MaterialApp` theme.

:::note
Support for Material 2 and configuring the `useMaterial3` property
will eventually be deprecated and removed.
:::

Also, some of the widgets couldn't merely be updated,
but needed a whole new implementation.
For this reason, your UI might look a little strange when
you see it running with Material 3.
To fix this, manually migrate to the new widgets, such as [`NavigationBar`][].

For more details, check out the [Material 3 umbrella issue][] on GitHub.

[`NavigationBar`]: https://api.flutter.dev/flutter/material/NavigationBar-class.html

## Timeline

Landed in version: 3.13.0-4.0.pre<br>
In stable release: 3.16

## References

Documentation:

* [Material Design for Flutter][]

API documentation:

* [`ThemeData.useMaterial3`][]

Relevant issues:

* [Material 3 umbrella issue][]
* [Add support for M3 motion][]

Relevant PRs:

* [Change the default for `ThemeData.useMaterial3` to true][]
* [Updated `ThemeData.useMaterial3` API doc, default is true][]


[Material 3 gallery]: https://github.com/flutter/samples/tree/main/material_3_demo
[Material 3 umbrella issue]: https://github.com/flutter/flutter/issues/91605
[Material Design for Flutter]: /ui/design/material
[`ThemeData.useMaterial3`]: https://api.flutter.dev/flutter/material/ThemeData/useMaterial3.html
[Add support for M3 motion]: https://github.com/flutter/flutter/issues/129942
[Change the default for `ThemeData.useMaterial3` to true]: https://github.com/flutter/flutter/pull/129724
[Updated `ThemeData.useMaterial3` API doc, default is true]: https://github.com/flutter/flutter/pull/130764