Use du to summarize disk usage one level below the current directory, then let sort put the largest totals first.

For du, -h prints human-readable units and -d 1 limits the result to direct children. For sort, -h understands units such as K, M, and G, while -r reverses the order.

du reports allocated disk usage, which can differ from apparent file size. The . row is the total for the whole tree, and hidden directories are included.

The short flags are supported by GNU and BSD tools. GNU du also accepts the more explicit --max-depth=1.