Перевод введенного числа (в метрах) в милю, ярд, фут, дюйм

from tkinter import *
root = Tk()
var=IntVar()
root.title('Конвертер')
root.geometry('500x250')
a = Label(text = 'Перевод массы', font = 'arial 16')
a.pack()
b = Entry(fg = 'black', bg = 'white', width = 9, font = 'arial 13')
b.pack()
 
r1 = Radiobutton(root, text='миля', font='arial 12', variable=var, value=1)
r2 = Radiobutton(root, text='ярд', font='arial 12', variable=var, value=2)
r3 = Radiobutton(root, text='фут', font='arial 12', variable=var, value=3)
r4 = Radiobutton(root, text='дюйм', font='arial 12', variable=var, value=4)
r1.pack()
r2.pack()
r3.pack()
r4.pack()
 
c = Entry(fg = 'black', bg = 'white', width = 9, font = 'arial 13')
c.pack()

from tkinter import *
root = Tk()
var=IntVar()
root.title('Конвертер')
root.geometry('500x250')
a = Label(text = 'Перевод длины', font = 'arial 16')
a.pack()
def convert(name, index, mode):
  c.delete(0,END)
  if text.get() == "":
    return
  value = float(text.get())
  if   var.get() == 1:
    value = value*0.000621371
  elif var.get() == 2:
    value = value*1.09361
  elif var.get() == 2:
    value = value*3.28084
  elif var.get() == 4:
    value = value*39.3701
  c.insert(0,str(value))
text = StringVar()
text.trace("w", convert)
b = Entry(fg = 'black', bg = 'white', width = 9, font = 'arial 13', textvariable=text)
b.pack()
var = IntVar(root)
var.set(1)
var.trace("w", convert)
r1 = Radiobutton(root, text='миля', font='arial 12', variable=var, value=1)
r2 = Radiobutton(root, text='ярд', font='arial 12', variable=var, value=2)
r3 = Radiobutton(root, text='фут', font='arial 12', variable=var, value=3)
r4 = Radiobutton(root, text='дюйм', font='arial 12', variable=var, value=4)
r1.pack()
r2.pack()
r3.pack()
r4.pack()
c = Entry(fg = 'black', bg = 'white', width = 9, font = 'arial 13')
c.pack()
root.mainloop()