Tkinter Pack

Summary: in this tutorial, you’ll learn about the Tkinter pack geometry manager and how to use it to arrange widgets on a window.

Introduction to the Tkinter pack geometry manager

So far, you have learned how to use the pack() method to add widgets to a window.

To arrange widgets on a window, you use geometry managers. The pack() method is one of three geometry managers in Tkinter. The other geometry managers are grid() and place().

The pack geometry manager has many configurations. The following are the most commonly used options: fill, expand, side, ipadx, ipady, padx, and pady.

Let’s start with a simple program to understand each option better.

Tkinter pack geometry manager example

The following shows how to use the pack geometry manager to arrange two Label widgets on the root window:

import tkinter as tk root = tk.Tk() root.title('Pack Demo') root.geometry("300x200") # box 1 box1 = tk.Label( root, text="Box 1", bg="green", fg="white" ) box1.pack( ipadx=10, ipady=10 ) # box 2 box2 = tk.Label( root, text="Box 2", bg="red", fg="white" ) box2.pack( ipadx=10, ipady=10 ) root.mainloop()
Code language: Python (python)

Output:

This example uses the ipadx and ipady for internal padding. These options create spaces between the labels and their borders.

As you can see, the pack geometry manager piles the label widgets on top of each other.

1) Using the fill option

The fill option accepts three values 'x', 'y', and 'both'. These options allow the widget to fill available space along the x-axis, y-axis, and both.

If you add the fill='x' to the first widget like this:

box1.pack( ipadx=10, ipady=10, fill='x' )
Code language: Python (python)

… you’ll see that the widget fills all available space across the x-axis:

However, if you change to fill='y' as follows:

box1.pack( ipadx=10, ipady=10, fill='y' )
Code language: Python (python)

… you’ll see that the first widget doesn’t fill all space vertically:

Basically, the pack geometry manager allocates space to each widget as highlighted in the following picture:

When you use the fill option, the area of each widget can fill is constrained by those allocated areas.

Using the expand option

The expand option allocates more available space to a widget.

If you add the expand option to the first widget:

box1.pack( ipadx=10, ipady=10, expand=True )
Code language: Python (python)

…you’ll get the following output:

The first widget takes all available space in the window except for the space allocated to the second widget.

Since the first widget doesn’t have the fill option, it floats in the middle of the allocated area.

If you set fill to 'both':

box1.pack( ipadx=10, ipady=10, fill='both', expand=True )
Code language: Python (python)

…you’ll see that the first widget fills up most of the window like this:

If you add the expand option to both widgets, the pack manager will allocate the space to them evenly. For example:

import tkinter as tk root = tk.Tk() root.title('Pack Demo') root.geometry("300x200") # box 1 box1 = tk.Label( root, text="Box 1", bg="green", fg="white" ) box1.pack( ipadx=10, ipady=10, expand=True, fill='both' ) # box 2 box2 = tk.Label( root, text="Box 2", bg="red", fg="white" ) box2.pack( ipadx=10, ipady=10, expand=True ) root.mainloop()
Code language: Python (python)

Output:

Notice that the second widget doesn’t use all allocated space because it doesn’t have the fill option.

When you set the expand to True for all widgets, the pack manager will allocate space to them evenly.

However, this is only true when all the widgets share the same anchor side.

Using side option

The side option specifies the alignment of the widget. It can be 'left', 'top', 'right', and 'bottom'.

The side defaults to 'top'. In other words, widgets are aligned to the top of their container.

The following example sets the side of the first widget to 'left':

import tkinter as tk root = tk.Tk() root.title('Pack Demo') root.geometry("300x200") # box 1 box1 = tk.Label( root, text="Box 1", bg="green", fg="white" ) box1.pack( ipadx=10, ipady=10, expand=True, fill='both', side='left' ) # box 2 box2 = tk.Label( root, text="Box 2", bg="red", fg="white" ) box2.pack( ipadx=10, ipady=10, expand=True, fill='both' ) root.mainloop()
Code language: Python (python)

Output:

In this example, the expand option may not work as you expected. The reason is that widgets have different sides.

To make their space even again, you can set the side of both widgets to 'left' or one is 'left' and the other is 'right':

import tkinter as tk root = tk.Tk() root.title('Pack Demo') root.geometry("300x200") # box 1 box1 = tk.Label( root, text="Box 1", bg="green", fg="white" ) box1.pack( ipadx=10, ipady=10, expand=True, fill='both', side='left' ) # box 2 box2 = tk.Label( root, text="Box 2", bg="red", fg="white" ) box2.pack( ipadx=10, ipady=10, expand=True, fill='both', side='left' ) root.mainloop()
Code language: Python (python)

Output:

When to use the pack geometry manager

The geometry manager is suitable for the following:

  • Placing widgets in a top-down layout.
  • Placing widgets side by side

See the following example:

import tkinter as tk from tkinter import ttk root = tk.Tk() root.title('Pack Demo') root.geometry("300x200") # place widgets top down label1 = tk.Label( root, text='Box 1', bg="red", fg="white" ) label1.pack( ipadx=10, ipady=10, fill='x' ) label2 = tk.Label( root, text='Box 2', bg="green", fg="white" ) label2.pack( ipadx=10, ipady=10, fill='x' ) label3 = tk.Label( root, text='Box 3', bg="blue", fg="white" ) label3.pack( ipadx=10, ipady=10, fill='x' ) # place widgets side by side label4 = tk.Label( root, text='Left', bg="cyan", fg="black" ) label4.pack( ipadx=10, ipady=10, expand=True, fill='both', side='left' ) label5 = tk.Label( root, text='Center', bg="magenta", fg="black" ) label5.pack( ipadx=10, ipady=10, expand=True, fill='both', side='left' ) label6 = tk.Label( root, text='Right', bg="yellow", fg="black" ) label6.pack( ipadx=10, ipady=10, expand=True, fill='both', side='left' ) root.mainloop()
Code language: Python (python)

Output:

Summary

  • Use Tkinter pack geometry manager to arrange widgets in a top-down layout or side by side.
  • Use the fill, expand, and side options of pack geometry manager to control how widgets arranged.
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