Tkinter Radiobutton: variable, value, command and Methods

A Tkinter Radiobutton is used when the user should select one option from a group of mutually exclusive choices. Radiobuttons in the same group share one Tkinter control variable, while each button has its own value.

When a Radiobutton is selected, its value is stored in the shared variable. The other buttons in that group are automatically deselected.

Basic Tkinter Radiobutton Example 🔝

The following example creates three Radiobuttons. All three share the same StringVar, so only one choice can be selected at a time.

import tkinter as tk

root=tk.Tk()
root.geometry(
    '350x150'
)

status=tk.StringVar(
    value=''
)

r1=tk.Radiobutton(
    root,
    text='Passed',
    variable=status,
    value='Passed'
)

r2=tk.Radiobutton(
    root,
    text='Failed',
    variable=status,
    value='Failed'
)

r3=tk.Radiobutton(
    root,
    text='Appearing',
    variable=status,
    value='Appearing'
)

r1.grid(
    row=0,
    column=0,
    padx=15,
    pady=30
)

r2.grid(
    row=0,
    column=1
)

r3.grid(
    row=0,
    column=2
)

root.mainloop()

Because the initial value is an empty string and none of the Radiobuttons has value='', the group starts with no selection.

How variable and value Work 🔝

Two Radiobutton options are especially important:

For example:

choice=tk.StringVar()

r1=tk.Radiobutton(
    root,
    text='Python',
    variable=choice,
    value='Python'
)

r2=tk.Radiobutton(
    root,
    text='PHP',
    variable=choice,
    value='PHP'
)

If the user selects Python:

choice.get()

returns:

Python

If PHP is selected, the same variable returns:

PHP

Why the Values Should Be Unique

A Radiobutton displays itself as selected when the shared variable equals its own value. Therefore, two Radiobuttons in one group should not normally use the same value.

Avoid this:

r1=tk.Radiobutton(
    root,
    text='Python',
    variable=choice,
    value=1
)

r2=tk.Radiobutton(
    root,
    text='PHP',
    variable=choice,
    value=1
)

Both buttons are testing the same shared variable against the same value, so the group no longer represents distinct choices correctly.

Radiobutton with StringVar 🔝

StringVar is convenient when the selected values are meaningful words.

import tkinter as tk

root=tk.Tk()

choice=tk.StringVar(
    value='Python'
)

languages=[
    'Python',
    'PHP',
    'JavaScript'
]

for column, language in enumerate(
    languages
):
    rb=tk.Radiobutton(
        root,
        text=language,
        variable=choice,
        value=language
    )

    rb.grid(
        row=0,
        column=column,
        padx=10,
        pady=20
    )

root.mainloop()

Python is selected when the window opens because:

choice=tk.StringVar(
    value='Python'
)

Radiobutton with IntVar 🔝

Use IntVar when each choice should store an integer.

status=tk.IntVar(
    value=-1
)

r1=tk.Radiobutton(
    root,
    text='Passed',
    variable=status,
    value=1
)

r2=tk.Radiobutton(
    root,
    text='Failed',
    variable=status,
    value=0
)

r3=tk.Radiobutton(
    root,
    text='Appearing',
    variable=status,
    value=5
)

Radiobutton with BooleanVar 🔝

BooleanVar can be used for a two-choice group because Boolean values provide only True and False.

import tkinter as tk

root=tk.Tk()

result=tk.BooleanVar(
    value=True
)

r1=tk.Radiobutton(
    root,
    text='Yes',
    variable=result,
    value=True
)

r2=tk.Radiobutton(
    root,
    text='No',
    variable=result,
    value=False
)

r1.pack()
r2.pack()

root.mainloop()

For groups with more than two choices, StringVar or IntVar is usually more suitable.

Set a Default Radiobutton Selection 🔝

Set the shared variable to the value of the button that should initially be selected.

choice=tk.StringVar(
    value='Python'
)

or after creating the variable:

choice.set(
    'Python'
)

Any Radiobutton using:

value='Python'

will display as selected.

Start with No Radiobutton Selected 🔝

Set the variable to a value that does not match any Radiobutton in the group.

StringVar

choice=tk.StringVar(
    value=''
)

If the button values are Python, PHP and JavaScript, none will match the empty string.

IntVar

choice=tk.IntVar(
    value=-1
)

If the actual button values are 0, 1 and 2, the value -1 leaves the group unselected.

Read and Change the Selected Value 🔝

Read the Selection

selected=choice.get()

print(
    selected
)

Change the Selection

choice.set(
    'PHP'
)

The Radiobutton whose value='PHP' becomes selected automatically.

Run a Function When a Radiobutton Is Selected 🔝

The command option runs a callback when the user invokes the Radiobutton.

import tkinter as tk

def show_selection():
    print(
        'Selected:',
        choice.get()
    )

root=tk.Tk()

choice=tk.StringVar(
    value='Python'
)

r1=tk.Radiobutton(
    root,
    text='Python',
    variable=choice,
    value='Python',
    command=show_selection
)

r2=tk.Radiobutton(
    root,
    text='PHP',
    variable=choice,
    value='PHP',
    command=show_selection
)

r1.pack()
r2.pack()

root.mainloop()

The callback receives no event argument. Read the shared variable with get() to determine which choice was selected.

Monitor Selection Changes with trace_add() 🔝

command responds to Radiobutton invocation. If you want to react whenever the associated variable changes, including changes made with set(), use trace_add().

import tkinter as tk

def selection_changed(*args):
    print(
        'New value:',
        choice.get()
    )

root=tk.Tk()

choice=tk.StringVar(
    value=''
)

choice.trace_add(
    'write',
    selection_changed
)

for value in [
    'Python',
    'PHP',
    'JavaScript'
]:
    tk.Radiobutton(
        root,
        text=value,
        variable=choice,
        value=value
    ).pack(
        anchor='w'
    )

root.mainloop()

*args accepts the arguments supplied by the Tkinter variable trace callback.

Reset All Radiobuttons in a Group 🔝

A reliable way to clear a group is to set the shared variable to a value that none of its Radiobuttons uses.

StringVar Group

choice.set(
    ''
)

IntVar Group

choice.set(
    -1
)

Choose a sentinel value that is not used by any actual choice.

Create Multiple Independent Radiobutton Groups 🔝

Different shared variables create different groups.

language=tk.StringVar()
level=tk.StringVar()

tk.Radiobutton(
    root,
    text='Python',
    variable=language,
    value='Python'
)

tk.Radiobutton(
    root,
    text='PHP',
    variable=language,
    value='PHP'
)

tk.Radiobutton(
    root,
    text='Beginner',
    variable=level,
    value='Beginner'
)

tk.Radiobutton(
    root,
    text='Advanced',
    variable=level,
    value='Advanced'
)

One language and one level can be selected because the two sets use different variables.

Copy a Selection Between Two Radiobutton Groups 🔝

import tkinter as tk

def copy_selection():
    group2.set(
        group1.get()
    )

root=tk.Tk()
root.geometry(
    '400x180'
)

group1=tk.StringVar(
    value='Passed'
)

group2=tk.StringVar(
    value='Passed'
)

options=[
    'Passed',
    'Failed',
    'Appearing'
]

for column, option in enumerate(
    options
):
    tk.Radiobutton(
        root,
        text=option,
        variable=group1,
        value=option,
        command=copy_selection
    ).grid(
        row=0,
        column=column,
        padx=10,
        pady=20
    )

    tk.Radiobutton(
        root,
        text=option,
        variable=group2,
        value=option
    ).grid(
        row=1,
        column=column,
        padx=10
    )

root.mainloop()

When a button in the first group is selected, its value is copied into the variable used by the second group.

Tkinter Radiobutton Methods 🔝

import tkinter as tk

def show_value():
    print(
        'Value:',
        choice.get()
    )

root=tk.Tk()
root.geometry(
    '500x220'
)

choice=tk.StringVar(
    value='MySQL'
)

r1=tk.Radiobutton(
    root,
    text='PHP',
    variable=choice,
    value='PHP',
    command=show_value
)

r2=tk.Radiobutton(
    root,
    text='MySQL',
    variable=choice,
    value='MySQL',
    command=show_value
)

r3=tk.Radiobutton(
    root,
    text='Python',
    variable=choice,
    value='Python',
    command=show_value
)

r1.grid(
    row=0,
    column=0,
    padx=15,
    pady=25
)

r2.grid(
    row=0,
    column=1
)

r3.grid(
    row=0,
    column=2
)

tk.Button(
    root,
    text='select()',
    command=r1.select
).grid(
    row=1,
    column=0
)

tk.Button(
    root,
    text='deselect()',
    command=r1.deselect
).grid(
    row=1,
    column=1
)

tk.Button(
    root,
    text='flash()',
    command=r1.flash
).grid(
    row=1,
    column=2
)

tk.Button(
    root,
    text='invoke()',
    command=r1.invoke
).grid(
    row=1,
    column=3
)

root.mainloop()

Enable or Disable Radiobuttons 🔝

Use state='disabled' to prevent user interaction. Restore the normal enabled state with state='normal'.

r1.config(
    state='disabled'
)

r1.config(
    state='normal'
)

Complete Example

import tkinter as tk

root=tk.Tk()

choice=tk.StringVar(
    value='Passed'
)

r1=tk.Radiobutton(
    root,
    text='Passed',
    variable=choice,
    value='Passed'
)

r2=tk.Radiobutton(
    root,
    text='Failed',
    variable=choice,
    value='Failed',
    state='disabled'
)

r1.pack()
r2.pack()

root.mainloop()

The classic Tk Radiobutton also understands an active state for its active visual appearance, but use normal when you want to enable a disabled button.

Radiobuttons with Built-in Bitmaps 🔝

import tkinter as tk

root=tk.Tk()
root.geometry(
    '220x150'
)

choice=tk.IntVar(
    value=-1
)

bitmaps=[
    ('info', 1),
    ('question', 2),
    ('warning', 3)
]

for column, data in enumerate(
    bitmaps
):
    bitmap_name, value=data

    tk.Radiobutton(
        root,
        bitmap=bitmap_name,
        variable=choice,
        value=value
    ).grid(
        row=0,
        column=column,
        padx=15,
        pady=40
    )

root.mainloop()

Pushbutton Style with indicatoron 🔝

The classic Tkinter Radiobutton normally displays a separate radio indicator. Setting indicatoron=0 removes the indicator and makes the complete widget appear more like a pushbutton.

import tkinter as tk

def selected():
    print(
        'Selected value:',
        choice.get()
    )

root=tk.Tk()
root.geometry(
    '500x150'
)

choice=tk.StringVar(
    value='Python'
)

options=[
    'PHP',
    'Python',
    'JSP'
]

for column, option in enumerate(
    options
):
    rb=tk.Radiobutton(
        root,
        text=option,
        variable=choice,
        value=option,
        command=selected,
        indicatoron=0,
        width=10,
        padx=5,
        pady=5
    )

    rb.grid(
        row=0,
        column=column,
        padx=8,
        pady=30
    )

root.mainloop()

The buttons are still mutually exclusive because they continue to share the same variable.

Create Radiobuttons Dynamically from Data 🔝

If the number of choices comes from a list, database query or another data source, create the Radiobuttons in a loop.

import tkinter as tk

root=tk.Tk()

choice=tk.StringVar(
    value=''
)

languages=[
    'Python',
    'PHP',
    'JavaScript',
    'SQL'
]

for row, language in enumerate(
    languages
):
    tk.Radiobutton(
        root,
        text=language,
        variable=choice,
        value=language
    ).grid(
        row=row,
        column=0,
        sticky='w'
    )

root.mainloop()

Only the data list has to change when more options are added.

Use Radiobutton Selection in an SQL Filter 🔝

A Radiobutton group can select a year that is later passed to a parameterized SQL query.

from datetime import datetime
import tkinter as tk

root=tk.Tk()
root.geometry(
    '450x180'
)

current_year=datetime.now().year

years=[
    current_year - 1,
    current_year,
    current_year + 1
]

selected_year=tk.IntVar(
    value=current_year
)

query_label=tk.Label(
    root,
    text='Select a year',
    bg='yellow',
    width=50
)

query_label.grid(
    row=1,
    column=0,
    columnspan=3,
    padx=5,
    pady=10
)

def update_query():
    query="SELECT * FROM my_tasks WHERE strftime('%Y', dt) = ?"
    params=(str(selected_year.get()),)

    query_label.config(
        text=f'{query}  {params}'
    )

for column, year in enumerate(
    years
):
    tk.Radiobutton(
        root,
        text=year,
        variable=selected_year,
        value=year,
        command=update_query
    ).grid(
        row=0,
        column=column,
        padx=10,
        pady=20
    )

root.mainloop()

The query and parameters can later be passed separately to the database API:

cursor.execute(
    query,
    params
)

This is preferable to manually concatenating user-controlled values into an SQL statement.

Use ttk.Radiobutton for Themed Interfaces 🔝

ttk.Radiobutton is the themed counterpart of the classic Tkinter Radiobutton. It uses the same important concepts: a shared variable and a unique value for each choice.

import tkinter as tk
from tkinter import ttk

root=tk.Tk()

choice=tk.StringVar(
    value='Python'
)

ttk.Radiobutton(
    root,
    text='Python',
    variable=choice,
    value='Python'
).pack(
    anchor='w'
)

ttk.Radiobutton(
    root,
    text='PHP',
    variable=choice,
    value='PHP'
).pack(
    anchor='w'
)

root.mainloop()

Classic options such as bg, fg, selectcolor and indicatoron are associated with the classic tk.Radiobutton. The themed ttk.Radiobutton is normally customized using ttk styles and states.

Common Tkinter Radiobutton Mistakes 🔝

1. Giving Every Radiobutton a Different Variable

This creates independent buttons rather than one mutually exclusive group.

For one group, use one shared variable:

choice=tk.StringVar()

r1=tk.Radiobutton(
    root,
    variable=choice,
    value='A'
)

r2=tk.Radiobutton(
    root,
    variable=choice,
    value='B'
)

2. Giving Two Buttons the Same value

Each choice in one group should normally use a different value.

3. Accidentally Selecting value=0 with IntVar

This can be unexpected:

choice=tk.IntVar()

r1=tk.Radiobutton(
    root,
    variable=choice,
    value=0
)

Because an IntVar starts at 0, this Radiobutton can initially match the variable.

Use an unmatched default:

choice=tk.IntVar(
    value=-1
)

4. Using BooleanVar for More Than Two Distinct Choices

A Boolean value only has two states. Use StringVar or IntVar for a larger group.

5. Expecting select() to Run command

select() updates the selection. Use invoke() when you also want the Radiobutton's command callback to run.

6. Confusing Radiobuttons with Checkbuttons

Radiobuttons are designed for one selection from a group. Checkbuttons allow independent selections and therefore can support multiple checked options at the same time.

7. Resetting with a Value Used by Another Button

To clear the group, set the shared variable to a value that none of the buttons uses.

8. Building SQL by String Concatenation

Keep SQL code and values separate and use database parameters where supported.

Exercise on Radiobuttons 🔝

1. Create one column of Radiobuttons representing programming languages and another column containing matching Checkbuttons. When the user selects a Radiobutton, select the matching Checkbutton. When the user changes the Radiobutton selection, clear the previous Checkbutton and select the new matching one.

Example: selecting the PHP Radiobutton selects the PHP Checkbutton. Changing the choice to Python clears PHP and selects Python.

Summary of Tkinter Radiobutton 🔝

• Radiobuttons are used for mutually exclusive choices.
• Buttons in one group share the same Tkinter control variable.
• Each Radiobutton should normally have a unique value.
• Selecting a button stores its value in the shared variable.
• Use get() to read the current selection.
• Use set() to change the selection programmatically.
• If the shared variable does not match any Radiobutton value, none of the buttons is selected.
• StringVar is convenient for descriptive text values.
• IntVar is useful for numeric values.
• An IntVar() normally starts at 0, so take care when one button also uses value=0.
• BooleanVar is practical for a two-choice True/False group.
• The command callback runs when a Radiobutton is invoked.
• trace_add() can monitor changes to the shared variable, including programmatic changes.
• select() selects a button without calling its command callback.
• invoke() selects the button and runs its command unless the widget is disabled.
• deselect() clears the selected Radiobutton.
• flash() changes the appearance temporarily without changing the final selection.
• Use state='disabled' and state='normal' to disable or enable a Radiobutton.
• indicatoron=0 gives the classic Radiobutton a pushbutton-style appearance.
• Different shared variables create independent Radiobutton groups.
• Radiobuttons can be generated dynamically from lists or database results.
• ttk.Radiobutton provides the themed Radiobutton widget.

Subhendu Mohapatra

Author & Instructor at plus2net

I write and maintain practical tutorials on Python, PHP, SQL, JavaScript, HTML, jQuery, and web development at plus2net. The tutorials focus on clear explanations, working examples, and code that readers can test and adapt while learning.

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