human-readable.js

function humanizeBytes(bytes, si) {
    unit = si ? 1e3 : 1024;
    var byteSuffix = (si ? 'b' : 'B');
    if (bytes < unit) {
        return bytes + byteSuffix;
    }
    
    var modifier = Math.floor(Math.log(bytes) / Math.log(unit));
    var prefix = (si ? 'kMGTPEZ' : 'KMGTPEZ')[modifier - 1];
    if (!si) {
      prefix += 'i';
    }
    return (bytes / Math.pow(unit, modifier)) + ' ' + prefix + byteSuffix;
}

human-readable.py

import math

def human_readable(bytes, si = True):
    unit = 1e3 if si else 1024

    if bytes < unit:
        return '%.1f %s' % (bytes, 'B')

    modifier = math.floor(math.log(bytes) / math.log(unit))
    pre = ('kMGTPEZ' if si else 'KMGTPEZ')[modifier - 1]
    if not si: 
        pre += 'i'
    return '%.1f %sB' % (bytes / math.pow(unit, modifier), pre)

sizes = list(map(lambda x: 1024 * math.pow(10, x), range(0, 10)))
for x in sizes: print(human_readable(x))