Output sums are rounded up to the nearest 1k unit (1024 bytes). By default, storage is assumed to be quantised in units of 1024 bytes. The -b option sets a different blocksize for quantisation, optionally suffixed by k for units of kilobytes; output is still in 1k units.
Du accepts the following options:
-a Output usage information for all subordinate files, not just directories.
-n Output just the filenames (but see the -t option below); implies -a .
-s Print only the summary line for each file .
-t Display the last-modified time for each file, not its size; when used with the -n option, outputs the filename, modification time (seconds since the epoch), size (in bytes), and checksum. The checksum field is always 0; it is a place-holder for a value computed by another command in a pipeline.
-u Display the last-accessed time for each file, not its size.