flutter set max width code example

Example 1: flutter column min height screen sixe

import 'dart:math'; // for max function

// Add the following around your column
LayoutBuilder(
  builder: (BuildContext context, BoxConstraints constraints) {
    return SingleChildScrollView(
      child: ConstrainedBox(
        constraints: BoxConstraints.tightFor(height: max(500, constraints.maxHeight)),
        child: Column(), // your column
      ),
    );
  },
);

Example 2: flutter set text width

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatefulWidget {
  @override
  MyAppState createState() {
    return new MyAppState();
  }
}

class MyAppState extends State {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: SafeArea(
          child: Center(
            child: Container(
              color: Colors.blue,
              width: 300.0,
              height: 200.0,
              child: FittedBox(
                fit: BoxFit.contain,
                child: Text("Whee"),
              ),
            ),
          ),
        ),
      ),
    );
  }
}