from tkinter import *

def convert_km_to_ml():
    km = textbox1.get()
    km = int(km)
    message = km * 0.6214
    textbox2.delete(0, 'end')
    textbox2.insert('end', str(message))
    textbox2.insert('end', " millas")

def convert_ml_to_km():
    ml = textbox1.get()
    ml = int(ml)
    message = round(ml * 1.6093, 3)
    textbox2.delete(0, 'end')
    textbox2.insert('end', str(message))
    textbox2.insert('end', " kilometros")

window = Tk()
window.title("Distancia")
window.geometry("260x200")

label1 = Label(text="Ingresa el valor a convertir:")
label1.place(x=30, y=20)

textbox1 = Entry()
textbox1.place(x=30, y=50, width=200, height=25)
textbox1["justify"] = "center"
textbox1.focus()

convert1 = Button(text="Convertir milas a kilometros", command=convert_ml_to_km)
convert1.place(x=30, y=80, width=200, height=25)

convert2 = Button(text="Convertir kilometros a milas", command=convert_km_to_ml)
convert2.place(x=30, y=110, width=200, height=25)

textbox2 = Entry()
textbox2.place(x=30, y=140, width=200, height=25)
textbox2["justify"] = "center"

window.mainloop()