Python: Age Calculator using Tkinter

Last Updated : 28 Apr, 2025

Prerequisites :Introduction to tkinter

Python offers multiple options for developing a GUI (Graphical User Interface). Out of all the GUI methods, Tkinter is the most commonly used method. It is a standard Python interface to the Tk GUI toolkit shipped with Python. Python with Tkinter outputs the fastest and easiest way to create GUI applications. Now, it’s up to the imagination or necessity of a developer, what he/she wants to develop using this toolkit.

To create a Tkinter :

Importing the module – Tkinter
Create the main window (container)
Add any number of widgets to the main window.
Apply the event Trigger on the widgets.

The GUI would look like below:

Let’s create a GUI based simple Age Calculator application that can calculate the age with respect to the given date and birth date, given by the user.

Below is the implementation :

Python3

# import all functions from the tkinter  from tkinter import * # import messagebox class from tkinter from tkinter import messagebox # Function for clearing the  # contents of all text entry boxes def clearAll() : # deleting the content from the entry box dayField.delete(0, END) monthField.delete(0, END) yearField.delete(0, END) givenDayField.delete(0, END) givenMonthField.delete(0, END) givenYearField.delete(0, END) rsltDayField.delete(0, END) rsltMonthField.delete(0, END) rsltYearField.delete(0, END) # function for checking error def checkError() : # if any of the entry field is empty # then show an error message and clear  # all the entries if (dayField.get() == "" or monthField.get() == "" or yearField.get() == "" or givenDayField.get() == "" or givenMonthField.get() == "" or givenYearField.get() == "") : # show the error message messagebox.showerror("Input Error") # clearAll function calling clearAll() return -1 # function to calculate Age  def calculateAge() : # check for error value = checkError() # if error is occur then return if value == -1 : return else : # take a value from the respective entry boxes # get method returns current text as string birth_day = int(dayField.get()) birth_month = int(monthField.get()) birth_year = int(yearField.get()) given_day = int(givenDayField.get()) given_month = int(givenMonthField.get()) given_year = int(givenYearField.get()) # if birth date is greater then given birth_month  # then donot count this month and add 30 to the date so  # as to subtract the date and get the remaining days  month =[31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31] if (birth_day > given_day): given_month = given_month - 1 given_day = given_day + month[birth_month-1] # if birth month exceeds given month, then  # donot count this year and add 12 to the  # month so that we can subtract and find out  # the difference  if (birth_month > given_month): given_year = given_year - 1 given_month = given_month + 12 # calculate day, month, year  calculated_day = given_day - birth_day; calculated_month = given_month - birth_month; calculated_year = given_year - birth_year; # calculated day, month, year write back # to the respective entry boxes # insert method inserting the  # value in the text entry box. rsltDayField.insert(10, str(calculated_day)) rsltMonthField.insert(10, str(calculated_month)) rsltYearField.insert(10, str(calculated_year)) # Driver Code if __name__ == "__main__" : # Create a GUI window gui = Tk() # Set the background colour of GUI window  gui.configure(background = "light green") # set the name of tkinter GUI window  gui.title("Age Calculator") # Set the configuration of GUI window gui.geometry("525x260") # Create a Date Of Birth : label  dob = Label(gui, text = "Date Of Birth", bg = "blue") # Create a Given Date : label givenDate = Label(gui, text = "Given Date", bg = "blue") # Create a Day : label day = Label(gui, text = "Day", bg = "light green") # Create a Month : label month = Label(gui, text = "Month", bg = "light green") # Create a Year : label year = Label(gui, text = "Year", bg = "light green") # Create a Given Day : label givenDay = Label(gui, text = "Given Day", bg = "light green") # Create a Given Month : label givenMonth = Label(gui, text = "Given Month", bg = "light green") # Create a Given Year : label givenYear = Label(gui, text = "Given Year", bg = "light green") # Create a Years : label rsltYear = Label(gui, text = "Years", bg = "light green") # Create a Months : label rsltMonth = Label(gui, text = "Months", bg = "light green") # Create a Days : label rsltDay = Label(gui, text = "Days", bg = "light green") # Create a Resultant Age Button and attached to calculateAge function resultantAge = Button(gui, text = "Resultant Age", fg = "Black", bg = "Red", command = calculateAge) # Create a Clear All Button and attached to clearAll function clearAllEntry = Button(gui, text = "Clear All", fg = "Black", bg = "Red", command = clearAll) # Create a text entry box for filling or typing the information.  dayField = Entry(gui) monthField = Entry(gui) yearField = Entry(gui) givenDayField = Entry(gui) givenMonthField = Entry(gui) givenYearField = Entry(gui) rsltYearField = Entry(gui) rsltMonthField = Entry(gui) rsltDayField = Entry(gui) # grid method is used for placing  # the widgets at respective positions  # in table like structure . dob.grid(row = 0, column = 1) day.grid(row = 1, column = 0) dayField.grid(row = 1, column = 1) month.grid(row = 2, column = 0) monthField.grid(row = 2, column = 1) year.grid(row = 3, column = 0) yearField.grid(row = 3, column = 1) givenDate.grid(row = 0, column = 4) givenDay.grid(row = 1, column = 3) givenDayField.grid(row = 1, column = 4) givenMonth.grid(row = 2, column = 3) givenMonthField.grid(row = 2, column = 4) givenYear.grid(row = 3, column = 3) givenYearField.grid(row = 3, column = 4) resultantAge.grid(row = 4, column = 2) rsltYear.grid(row = 5, column = 2) rsltYearField.grid(row = 6, column = 2) rsltMonth.grid(row = 7, column = 2) rsltMonthField.grid(row = 8, column = 2) rsltDay.grid(row = 9, column = 2) rsltDayField.grid(row = 10, column = 2) clearAllEntry.grid(row = 12, column = 2) # Start the GUI gui.mainloop()