Python Tutorial



Python Tutorial

Calculator Program in Python

Python, as a versatile and beginner-friendly programming language, is an excellent choice for developing calculator applications. These calculator programs are fundamental tools in software development, designed to perform mathematical calculations. In this comprehensive article, we will explore how to create two types of calculator program in Python: a simple command-line calculator and a graphical user interface (GUI) calculator. 


Calculator programs are indispensable in software development. They perform various mathematical calculations and are implemented in a myriad of ways. Here are two key approaches to build a calculator project in python with source code:

  • Simple Calculator: This is a basic command-line calculator that handles fundamental arithmetic operations such as addition, subtraction, multiplication, and division.

  • GUI Calculator: A graphical user interface (GUI) calculator is more user-friendly and interactive. It allows users to perform calculations by clicking on buttons and is often created using Python libraries like Tkinter. This type of calculator provides a more engaging and intuitive user experience.

Both simple and GUI-based calculators have their unique advantages and use cases. Explore the programs to gain a deeper understanding of Python's capabilities and create tools according to user preferences.

What is a Calculator Program in Python?

A calculator program in Python is a software application designed to perform mathematical calculations. It can handle a wide range of arithmetic operations, including but not limited to:

  • Addition

  • Subtraction

  • Multiplication

  • Division

  • Exponentiation

  • Square root

  • Trigonometric functions (e.g., sine, cosine, tangent)

  • Logarithmic functions

  • Memory functions (e.g., storing and recalling values)

Python Program to Make a Simple Calculator

Let's start with a simple calculator in python assignment expert. This calculator will be capable of performing basic arithmetic operations such as addition, subtraction, multiplication, and division. 

Steps to Create a Simple Command-Line Calculator in Python:

  1. Define Arithmetic Functions: Begin by defining functions for the basic arithmetic operations you want the calculator to perform, such as addition, subtraction, multiplication, and division.

  2. User Interface Setup: Create a user-friendly interface for the command-line calculator. You can use a while loop to repeatedly prompt the user for input and display options for different operations.

  3. User Input Handling: Within the loop, handle user input to determine the selected operation. You can provide options for the user to input numbers and choose between different operations.

  4. Function Calls: Based on the user's input, call the corresponding arithmetic function defined in step 1. Ensure proper error handling, such as division by zero.

  5. Display Results: Display the calculated result to the user. This may involve printing the result to the console or using a print statement to show the output.

  6. Loop Continuation: Allow the user to continue performing calculations or choose to quit the program. Use a condition in the while loop to decide whether to continue or exit the calculator.

Below is an example code for a basic Python calculator:


def add(x, y):
    return x y

def subtract(x, y):
    return x - y

def multiply(x, y):
    return x * y

def divide(x, y):
    if y == 0:
        return "Division by zero is not allowed."
    return x / y

while True:
    print("Enter 'add' for addition")
    print("Enter 'subtract' for subtraction")
    print("Enter 'multiply' for multiplication")
    print("Enter 'divide' for division")
    print("Enter 'quit' to end the program")
    user_input = input(": ")

    if user_input == "quit":
    elif user_input in ["add", "subtract", "multiply", "divide"]:
        num1 = float(input("Enter the first number: "))
        num2 = float(input("Enter the second number: "))

        if user_input == "add":
            print("Result: ", add(num1, num2))
        elif user_input == "subtract":
            print("Result: ", subtract(num1, num2))
        elif user_input == "multiply":
            print("Result: ", multiply(num1, num2))
        elif user_input == "divide":
            print("Result: ", divide(num1, num2))
        print("Invalid input")

In this example, we define four functions (add, subtract, multiply, and divide) to handle the respective arithmetic operations. We then use a while loop to create an interactive menu for the user. The user can enter their choice of operation and two numbers to perform the calculation.

The calculator ensures that division by zero is not allowed, which is an important aspect of error handling.

Example Usage:

Let's illustrate how the simple calculator works with an example:

Addition Operation
Enter 'add' for addition
Enter 'subtract' for subtraction
Enter 'multiply' for multiplication
Enter 'divide' for division
Enter 'quit' to end the program
: add
Enter the first number: 10
Enter the second number: 5
Result: 15.0

Subtraction Operation


Enter 'add' for addition

Enter 'subtract' for subtraction

Enter 'multiply' for multiplication

Enter 'divide' for division

Enter 'quit' to end the program

: subtract

Enter the first number: 20

Enter the second number: 8

Result: 12.0

Multiplication Operation


Enter 'add' for addition

Enter 'subtract' for subtraction

Enter 'multiply' for multiplication

Enter 'divide' for division

Enter 'quit' to end the program

: multiply

Enter the first number: 6

Enter the second number: 4

Result: 24.0

Division Operation


Enter 'add' for addition

Enter 'subtract' for subtraction

Enter 'multiply' for multiplication

Enter 'divide' for division

Enter 'quit' to end the program

: divide

Enter the first number: 12

Enter the second number: 3

Result: 4.0

Python Program to Make GUI Calculator

Now, let's move on to creating a graphical user interface (GUI) calculator in Python using the Tkinter library. Tkinter is a popular library for creating GUI applications in Python.

Steps to Create calculator in Python tkinter:

  1. Import Required Libraries: Start by importing the necessary libraries, primarily Tkinter, for creating the graphical user interface.

  2. Create the Main Window: Initialize the main window for the GUI calculator. Customize its title, size, and any other visual elements as desired.

  3. Create Input Field: Add an input field (often a tk.Entry widget) where users can input numbers and operations.

  4. Create Buttons: Create buttons for digits, arithmetic operations, and other functions (e.g., clear, equals). Use tk.Button widgets for this purpose. Assign appropriate functions to these buttons.

  5. Button Functions: Define functions that handle button clicks. For instance, a button that represents a digit should append that digit to the input field.

  6. Evaluate and Display Results: Implement the functionality to evaluate the input expression. You can use Python's eval function to perform the calculation, and then display the result in the input field.

  7. Error Handling: Include error handling to manage cases such as division by zero or invalid expressions. Display error messages as needed.

  8. Event Loop: Start the Tkinter event loop (mainloop()) to make the GUI calculator interactive. This loop ensures that the application remains responsive to user actions.

Below is a python code for calculator GUI:

import tkinter as tk

def button_click(number):
    current = entry.get()
    entry.delete(0, tk.END)
    entry.insert(0, current str(number))

def clear():
    entry.delete(0, tk.END)

def evaluate():
        result = eval(entry.get())
        entry.delete(0, tk.END)
        entry.insert(0, result)
        entry.delete(0, tk.END)
        entry.insert(0, "Error")

# Create the main window
window = tk.Tk()

# Create an entry widget for input
entry = tk.Entry(window, width=20, borderwidth=5)
entry.grid(row=0, column=0, columnspan=4)

# Create buttons for digits and operations
button_texts = [
    "7", "8", "9", "/",
    "4", "5", "6", "*",
    "1", "2", "3", "-",
    "0", "C", "=", " "

row, col = 1, 0
for text in button_texts:
    if text == "C":
        button = to.Button(window, text=text, padx=20, pady=20, command=clear)
    elif text == "=":
        button = to.Button(window, text=text, padx=20, pady=20, command=evaluate)
        button = to.Button(window, text=text, padx=20, pady=20, command=lambda t=text: button_click(t))
    button.grid(row=row, column=col)
    col = 1
    if col > 3:
        col = 0
        row = 1


In this Python code for calculator GUI example, we use the Tkinter library to create a GUI window. We create an entry widget for input, and buttons for digits, operators, and the clear and evaluate functions. When the user clicks a button, the button_click function appends the clicked number or operator to the input field, the clear function clears the input, and the evaluate function calculates and displays the result.

Advanced Features and Customization

The Python calculator online programs we've presented are solid starting points, but you can further enhance and customize them to suit your needs. Here are some ideas for advanced features and customization of simple calculator command in python skillrack and advanced feature calculator:

  • Scientific Functions: Extend the simple calculator to include advanced mathematical functions like trigonometric (sine, cosine, tangent), logarithmic, and exponential functions.

  • Memory Functions: Implement memory functions, such as storing and recalling values. This can be useful for multi-step calculations.

  • History Feature: Create a history feature that stores past calculations and results, allowing users to review and reuse them.

  • Custom Themes: Customize the appearance of your GUI calculator by adjusting colors, fonts, and layout. Tkinter provides options to change the look and feel of your application. You can also explore themes and styles to create a more visually appealing calculator.

  • Keyboard Shortcuts: Allow users to use keyboard inputs alongside mouse interactions for efficiency. Set up event bindings to map keyboard keys to specific functions.

  • Error Handling: Enhance error handling by providing meaningful error messages and ensuring the calculator gracefully handles unexpected inputs.

  • Unit Conversion: Create a calculator that can perform unit conversions (e.g., converting between Celsius and Fahrenheit, or between different measurement units).


In conclusion, this calculator program in Python article highlights the Python language pivotal role in calculator program development. We've delved into the creation of a fundamental command-line calculator and an interactive GUI calculator, showcasing Python's adaptability in this domain. Whether you're just beginning your programming journey or crafting user-friendly interfaces, Python is a robust choice. 


1. How can I allow the user to use keyboard inputs for my GUI calculator created with Tkinter?

You can enable keyboard inputs for your Tkinter-based GUI calculator by setting up event bindings. Map keyboard keys to the functions you want them to trigger, such as digits, operators, or the equals sign.

2. What are some best practices for designing a user-friendly GUI calculator in Python?

Some best practices include providing clear labels and visual feedback, organizing the user interface logically, ensuring responsiveness, and handling errors gracefully. User experience and intuitive design should be a top priority.

3. Can I create a calculator program for specific industries like finance or engineering in Python?

Yes, Python is a versatile language, and you can create specialized calculator programs for various industries. You'll need to tailor your calculator to the specific needs and requirements of the target users, incorporating relevant formulas and functions.

4. How can I implement a history feature in my calculator program to store past calculations and results?

You can implement a history feature by using data structures like lists or databases to store previous calculations and results. Create a section in your calculator interface to display and navigate through the stored history.

5. Are there any open-source calculator projects in Python that I can use or contribute to?

Yes, there are open-source calculator projects on platforms like GitHub. These projects often cover a wide range of features and use cases. You can use them as references, contribute to their development, or even fork them to create your own customized calculator.

Leave a Reply

Your email address will not be published. Required fields are marked *