sub-directory file size - recursive

size.py

import os

mb_scale_factor: float = pow(1024, 2) # If you want result expressed in MB

def get_dir_size(path: str) -> float:
    total: int = 0
    with os.scandir(path) as it:
        for entry in it:
            if entry.is_file():
                total += entry.stat().st_size
            elif entry.is_dir():
                total += get_dir_size(entry.path)
    return total/mb_scale_factor

main_folder: str = "path/to/main_folder"

with os.scandir(main_folder) as it:
    for entry in it:
        if entry.is_dir() and not entry.name.startswith("."):
            print(f"{entry.name}: {round(get_dir_size(entry.path), 2)} MB")