Window size and position in inch or points

Question

I was able to figure out how to set widget position and dimensions in other units:

import tkinter as tk
root = tk.Tk()
root.geometry("200x100+400+200")
btn = tk.Button(text="Button")
btn.place(x='20p', y='20p', width='70p', height='20p')
root.mainloop()

... and I would like to do the same with the window. However, geometry does not allow for units like root.geometry("200px100p+400p+200p"). How can I set the window size using inch or points?