Welcome folks today in this blog post we will be building advanced unit converter gui desktop app in tkinter. All the full source code of application is given below.

Get Started

In order to get started you need to make an app.py file and copy paste the following code

app.py

from tkinter import *

# Conversion factors
unit_dict = {
    "cm" : 0.01,
    "m" : 1.0,
    "km": 1000.0,
    "feet": 0.3048,
    "miles": 1609.344,
    "inches": 0.0254,
    "grams" : 1.0,
    "kg" : 1000.0,
    "quintals": 100000.0,
    "tonnes" : 1000000.0,
    "pounds" : 453.592,
    "sq. m" : 1.0,
    "sq. km": 1000000.0,
    "are" : 100.0,
    "hectare" : 10000.0,
    "acre": 4046.856,
    "sq. mile" : 2590000.0,
    "sq. foot" : 0.0929,
    "cu. cm" : 0.001,
    "Litre" : 1.0,
    "ml" : 0.001,
    "gallon": 3.785
}

lengths = ["cm", "m", "km", "feet", "miles", "inches",]
weights = ["kg", "grams", "quintals", "tonnes", "pounds",]
temps = ["Celsius", "Fahrenheit"]
areas = ["sq. m", "sq. km", "are", "hectare", "acre", "sq. mile", "sq. foot"]
volumes = ["cu. cm", "Litre", "ml", "gallon"]

# Options for drop-down menu
OPTIONS = ["select units",
            "cm",
            "m",
            "km",
            "feet",
            "miles",
            "inches",
            "kg",
            "grams",
            "quintals",
            "tonnes",
            "pounds",
            "Celsius",
            "Fahrenheit",
            "sq. m",
            "sq. km",
            "are",
            "hectare",
            "acre",
            "sq. mile",
            "sq. foot",
            "cu. cm",
            "Litre",
            "ml",
            "gallon"]

# Main window
root = Tk()
root.geometry("400x350")
root.title("Unit Converter")
root['bg'] = 'pink'

def ok():
    inp = float(inputentry.get())
    inp_unit = inputopt.get()
    out_unit = outputopt.get()

    cons = [inp_unit in lengths and out_unit in lengths,
    inp_unit in weights and out_unit in weights,
    inp_unit in temps and out_unit in temps,
    inp_unit in areas and out_unit in areas,
    inp_unit in volumes and out_unit in volumes]

    if any(cons): # If both the units are of same type, do the conversion
        if inp_unit == "Celsius" and out_unit == "Fahrenheit":
            outputentry.delete(0, END)
            outputentry.insert(0, (inp * 1.8) + 32)
        elif inp_unit == "Fahrenheit" and out_unit == "Celsius":
            outputentry.delete(0, END)
            outputentry.insert(0, (inp - 32) * (5/9))
        else:
            outputentry.delete(0, END)
            outputentry.insert(0, round(inp * unit_dict[inp_unit]/unit_dict[out_unit], 5))

    else: # Display error if units are of different types
        outputentry.delete(0, END)
        outputentry.insert(0, "ERROR")

inputopt = StringVar()
inputopt.set(OPTIONS[0])

outputopt = StringVar()
outputopt.set(OPTIONS[0])

# Widgets
inputlabel = Label(root, text = "Input")
inputlabel.grid(row = 0, column = 0, pady = 20)

inputentry = Entry(root, justify = "center", font = "bold")
inputentry.grid(row = 1, column = 0, padx = 35, ipady = 5)

inputmenu = OptionMenu(root, inputopt, *OPTIONS)
inputmenu.grid(row = 1, column = 1)
inputmenu.config(font = "Arial 10")

outputlabel = Label(root, text = "Output")
outputlabel.grid(row = 2, column = 0, pady = 20)

outputentry = Entry(root, justify = "center", font = "bold")
outputentry.grid(row = 3, column = 0, padx = 35, ipady = 5)

outputmenu = OptionMenu(root, outputopt, *OPTIONS)
outputmenu.grid(row = 3, column = 1)
outputmenu.config(font = "Arial 10")

okbtn = Button(root, text = "OK", command = ok, padx = 80, pady = 2)
okbtn.grid(row = 4, column = 0, columnspan = 2, pady = 50)

root.mainloop()

Now if you execute the python script by typing the below command as shown below

python app.py