Make container widget fill parent vertically

To stretch the container to full height of the parent use property constraints:BoxConstraints.expand() in container widget. Container occupy the complete space independent of the of child widget

Container(
  color: Colors.green,
  child: Text("Flutter"),
  constraints: BoxConstraints.expand(),
)

Please refer the link Container Cheat sheet for more about container

Simply pass in: double.infinity.

If you want a Container to fill all available space, you can just pass in:

width: double.infinity,
height: double.infinity

Explanation:

In Flutter, a child widget cannot exceed the "layout constraints" imposed by its parent widget. During the layout phase, Flutter engine uses a constraint solver to automatically correct "out-of-bound" values into what's allowed by its parent constraints.

For example, if you have a Container that's 50x50, and for its child, you pass in another Container that's 300x300, the inner container will be automatically corrected to "not exceed its parent", thus 50x50. Therefore, using sufficiently large values would always make sure you "fill parent".

In fact, even BoxConstraints.expand() exploits the same idea internally. If you open up the source code of expand(), you will see:

  /// Creates box constraints that expand to fill another box constraints.
  ///
  /// If width or height is given, the constraints will require exactly the
  /// given value in the given dimension.
  const BoxConstraints.expand({
    double width,
    double height,
  }) : minWidth = width ?? double.infinity,
       maxWidth = width ?? double.infinity,
       minHeight = height ?? double.infinity,
       maxHeight = height ?? double.infinity;

So if you are absolutely certain you want to fill all spaces, you can intuitively pass in a number bigger than the parent (or larger than the whole screen), like double.infinity.

The trick is to combine an IntrinsicHeight widget and a Row with crossAxisAlignment: CrossAxisAlignment.stretch

This force the children of Row to expand vertically, but Row will take the least amount of vertical space possible.

Card(
  child: IntrinsicHeight(
    child: Row(
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: <Widget>[
        Container(
          width: 20.0,
          color: Colors.amber,
        ),
        // Expanded(...)
      ],
    ),
  )
)

As of Jan 2020 the simplest is to use an Expanded Widget

Expanded(flex: 1,
         child: Container(..),
            ),

https://api.flutter.dev/flutter/widgets/Expanded-class.html