How to Pre-size a Tkinter Image Label with a Placeholder PhotoImage and Keep Your GUI Stable

Fix Tkinter image preview layout shifts: pre-size the Label with an empty PhotoImage. Learn why it collapses without content and keep your Python GUI stable.

Pre-sizing a Tkinter image preview often surprises developers: a Label meant to host a user-uploaded picture remains invisible and occupies no space until an image is actually loaded. Wrapping it in a Frame with explicit dimensions doesn’t help either. If your UI shifts around or compresses other controls only after the first upload, you’re looking at this exact behavior.

The setup that exhibits the issue

The following snippet wires a file picker to load an image into a label. Until a picture is chosen, the label is effectively size-less and doesn’t reserve space in the layout.

from tkinter import filedialog
from tkinter import *
from PIL import Image, ImageTk
# ---------- actions ----------
def on_pick_image():
    chosen_path = filedialog.askopenfilename()
    if chosen_path:
        pil_img = Image.open(chosen_path)
        tk_pic = ImageTk.PhotoImage(pil_img)
        preview_lbl.image = tk_pic
        preview_lbl.config(image=tk_pic)
# ---------- ui ----------
root_win = Tk()
canvas_box = Frame(root_win, width=500, height=500)
preview_lbl = Label(canvas_box)
btn_load = Button(root_win, text='Upload Image', command=on_pick_image)
canvas_box.grid(column=3, row=2, columnspan=5, rowspan=10, padx=50)
preview_lbl.pack()
btn_load.grid(column=1, row=1, padx=60, pady=60)
root_win.mainloop()

What’s actually happening

When the image label has no content, it doesn’t take space. Giving it a Frame wrapper with width and height does not change this behavior. The outcome is a layout that only expands once the first image is loaded, which can also make other controls appear to no longer fit after the sudden resize.

The fix

Assign an image to the label from the start, even if it’s just an empty PhotoImage. Once the label has an image, its width and height work as expected. You can also drop manual dimensions on the frame if they’re not needed.

from tkinter import filedialog
from tkinter import *
from PIL import Image, ImageTk
# ---------- actions ----------
def on_pick_image():
    chosen_path = filedialog.askopenfilename()
    if chosen_path:
        pil_img = Image.open(chosen_path)
        tk_pic = ImageTk.PhotoImage(pil_img)
        preview_lbl.image = tk_pic
        preview_lbl.config(image=tk_pic)
# ---------- ui ----------
root_win = Tk()
canvas_box = Frame(root_win)  # explicit width/height not really needed
preview_lbl = Label(canvas_box, image=PhotoImage(), width=500, height=500)
btn_load = Button(root_win, text='Upload Image', command=on_pick_image)
canvas_box.grid(column=3, row=2, columnspan=5, rowspan=10, padx=50)
preview_lbl.pack()
btn_load.grid(column=1, row=1, padx=60, pady=60)
root_win.mainloop()

Why this matters

A UI that morphs after the first user action is jarring. By reserving space for the image preview up front, the interface remains stable, predictable, and easier to reason about. Once the preview area has a fixed footprint, subsequent content fits consistently around it. If you later notice that other elements seem not to fit after making the image area large, that becomes a straightforward layout consideration now that the preview has a defined size.

Takeaway

Initialize the Label with an image immediately. With an initial PhotoImage in place, the label respects width and height from the beginning, your layout stays stable, and the image preview behaves the way you expect when the user uploads a file.