My JREN.BAT utility can be used to get a list of folders with sizes. It is a hybrid JScript/batch script that runs natively on any Windows machine from XP onward.
JREN does not conveniently convert to MB (or any other unit) - it simply lists the size in bytes. But it sure is convenient (and comparatively fast) to get the listing:
jren "$" "' # '+size()" /d /j /list /p "d:\temp" >"C:\folderList.txt"
You might consider putting the folder size first, space padded to a fixed width that exceeds the biggest folder, followed by the folder name. I find this format much easier to read, and it is still easy to parse:
jren "^" "size(' ')+' '" /d /j /list /p "d:\temp" >"C:\folderList.txt"
The output would look something like this
1852 SomeFolderName
1616869 Another folder name
137764 yetAnother
Since JREN is a batch file, you must use CALL JREN if you put the command within another batch script.