Converter Pesos usando Tkinter

 

from tkinter import *

root =Tk()
class peso():
    def clearTextInput(self):
        self.grama.delete("1.0", "end")
    def __init__(self):
        self.root = root
        self.janela()
        self.pesos()
        root.mainloop()
    def janela(self):
        self.root.title("Peso")
        self.root.geometry("400x300")
        self.root.resizable(False, False)
    def pesos(self):

        # Preço do Produto
        self.kg = DoubleVar()
        self.lb_kg = Label(text=" Peso em kg ",
                                           font=("Helvetica", '10'), bg="#4c4c4c",fg='#ffffff')
        self.lb_kg.place(relx=0.1, rely=0.05)
        self.kg_entry = Entry(textvariable=self.kg)
        self.kg_entry.place(relx=0.4, rely=0.05)
        # Butão de Converter o Peos
        self.bt_calcular = Button(text="Converter", bd=2,
                                  font=('verdana', '8', 'bold'), bg='gray18',
                                  fg='white',
                                  command=self.butao1)
        self.bt_calcular.place(relx=0.45, rely=0.2, relwidth=0.2, relheight=0.1)
        #  Grama
        self.grama = StringVar()

        self.lb_grama = Label(text="Grama",
                                  font=("Helvetica", '10', 'italic'))
        self.lb_grama.place(relx=0.15, rely=0.4)
        self.grama_resultado = Label(textvariable=self.grama, font=("Helvetica", '8'))
        self.grama_resultado.place(relx=0.35, rely=0.4)

        #  Pound
        self.pounds = StringVar()
        self.lb_pound = Label(text="Pound",
                              font=("Helvetica", '10', 'italic'))
        self.lb_pound.place(relx=0.15, rely=0.55)
        self.pound_resultado = Label(textvariable=self.pounds, font=("Helvetica", '8'))
        self.pound_resultado.place(relx=0.35, rely=0.55)

        #  Onça
        self.onca = StringVar()
        self.lb_onca = Label(text="Onça",
                              font=("Helvetica", '10', 'italic'))
        self.lb_onca.place(relx=0.15, rely=0.65)
        self.onca_resultado = Label(textvariable=self.onca, font=("Helvetica", '8'))
        self.onca_resultado.place(relx=0.35, rely=0.65)

    def butao1(self):
        kgs = self.kg.get()
        gram =round((kgs*1000),3)
        pound = round((kgs * 2.20462), 3)
        ounce = round((kgs * 35.274), 3)
        return self.grama.set(gram), self.pounds.set(pound), self.onca.set(ounce)
peso()