friendly-filesize.php

<?php

function humanize_filesize($size, $precision = 0) {
    if ($size !== 0) {
        $base = log($size) / log(1024);
        $units = array('B', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB');
        $size = round(pow(1024, $base - floor($base)), $precision);
        $unit = $units[floor($base)];
    } else {
        $unit = 'B';
    }

    return "{$size} {$unit}";
}