humnan_readable_filesize.py

def sizeof_human(numbytes):
    ''' Human-readable size strings '''
    if numbytes < 0:    # urlretrieve passes -1 for totalsize if it can't get the filesize from the server
        return '???'

    for x in ['bytes','KB','MB','GB','TB','PB']:
        if numbytes < 1024.0:
            return "%3.2f%s" % (numbytes, x)
        numbytes /= 1024.0
    else:
        return "Exabytes!"