How to specify where a Tkinter window opens?

root.geometry('250x150+0+0')

The first two parameters are the width and height of the window. The last two parameters are x and y screen coordinates. You can specify the required x and y coordinates

This answer is based on Rachel's answer. Her code did not work originally, but with some tweaking I was able to fix the mistakes.

import tkinter as tk


root = tk.Tk() # create a Tk root window

w = 800 # width for the Tk root
h = 650 # height for the Tk root

# get screen width and height
ws = root.winfo_screenwidth() # width of the screen
hs = root.winfo_screenheight() # height of the screen

# calculate x and y coordinates for the Tk root window
x = (ws/2) - (w/2)
y = (hs/2) - (h/2)

# set the dimensions of the screen 
# and where it is placed
root.geometry('%dx%d+%d+%d' % (w, h, x, y))

root.mainloop() # starts the mainloop

If you would like the window to be centered, this type of function may help you:

def center_window(size, window) :
    window_width = size[0] #Fetches the width you gave as arg. Alternatively window.winfo_width can be used if width is not to be fixed by you.
    window_height = size[1] #Fetches the height you gave as arg. Alternatively window.winfo_height can be used if height is not to be fixed by you.
    window_x = int((window.winfo_screenwidth() / 2) - (window_width / 2)) #Calculates the x for the window to be in the centre
    window_y = int((window.winfo_screenheight() / 2) - (window_height / 2)) #Calculates the y for the window to be in the centre

    window_geometry = str(window_width) + 'x' + str(window_height) + '+' + str(window_x) + '+' + str(window_y) #Creates a geometric string argument
    window.geometry(window_geometry) #Sets the geometry accordingly.
    return

Here, the window.winfo_screenwidth function is used for getting the width of the device screen. And the window.winfo_screenheight function is used for getting the height of the device screen.

Here you can call this function and pass a tuple with the (width, height) of the screen as the size.

You can customize the calculation as much as you want and it will change accordingly.

Try this

import tkinter as tk


def center_window(width=300, height=200):
    # get screen width and height
    screen_width = root.winfo_screenwidth()
    screen_height = root.winfo_screenheight()

    # calculate position x and y coordinates
    x = (screen_width/2) - (width/2)
    y = (screen_height/2) - (height/2)
    root.geometry('%dx%d+%d+%d' % (width, height, x, y))


root = tk.Tk()
center_window(500, 400)
root.mainloop()

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