How to get AppBar height in Flutter?

This is not an ideal way, I think, but it will work.

Firstly declare the AppBar widget that you will use in your Scaffold.

Widget demoPage() {
  AppBar appBar = AppBar(
    title: Text('Demo'),
  );
  return Scaffold(
    appBar: appBar,
    body: /*
    page body
    */,
  );
}

Now you can get the height of your appBar using its preferredSized:

double height = appBar.preferredSize.height;

You can use this height to reduce from the screen height.

final double height = MediaQuery.of(context).size.height;

you can use this :

var height = AppBar().preferredSize.height;

this way is very sample and easy

There is no need to store the AppBar instance, or to create a dummy one to get the height. Also, AppBar.preferredSize will always return the same value of 56.0, which is the standard of Material Design, and this value will not be always usable for some cases (it lacks the height of the status bar for example).

Since an AppBar is surely used with a Scaffold, IMHO, the smarter way to get the real AppBar height (the distance between the top of the device and the top of the Scaffold body) is to use:

double height = Scaffold.of(context).appBarMaxHeight;

With this, the computed height will include (independently of the platform):

The status bar height

The app bar height

The bottom app bar widget height if any (ex. TabBar)

Hope this will help!

There is a constant for the normal toolbar height: kToolbarHeight

Just watch in AppBar

MediaQuery.of(context).padding.top + kToolbarHeight

Get body height:

MediaQuery.of(context).size.height - (MediaQuery.of(context).padding.top + kToolbarHeight)

I hope, this solution will also help you. Thanks to ask this question.

AppBar has a fixed height of 56.

You should create your own appbar implementing PreferredSizeWidget

class TestAppBar extends StatelessWidget implements PreferredSizeWidget {
  @override
  Widget build(BuildContext context) {
    return AppBar(
      title: Text('TEST'),
      centerTitle: true,
    );
  }

  @override
  Size get preferredSize => Size.fromHeight(34);
}

You can get height of AppBar by using:

double height = appBar.preferredSize.height;

Make sure you have declared AppBar widget.

You can use this:

  @override
  final Size preferredSize; // default is 56.0

  WidgetAppBar({@required this.appBarTitle, @required this.appBarColor, Key key}) : preferredSize = Size.fromHeight(40), super(key: key);

Use preferred size

//defined as
Size preferredSize

preferred size is a size whose height is the sum of kToolbarHeight and the bottom widget's preferred height.

Scaffold uses this size to set its app bar's height.

It is defined like below in app bar class which implement PreferredSizeWidget

 preferredSize = new Size.fromHeight(kToolbarHeight + (bottom?.preferredSize?.height ?? 0.0))

a link for example ...

https://github.com/flutter/flutter/blob/master/packages/flutter/lib/src/material/app_bar.dart

This will give height of appbar or statusbar

var height = MediaQuery.of(context).padding.top;

However, this will work only in mobile devices, other devices don't have status bar