du is your friend. If you just want doto know the total size of a directory then jump into it and run:
du -hs If you also would like to know which sub-folders spendtake up how much disk space?! You could extend this command to:
du -h --max-depth=1 | sort -hr which will give you the size of all sub-folders (level 1). The output will be sorted (largest folder on top).