Human Readable File Size with PHP

gistfile1.php

<?php
# http://jeffreysambells.com/2012/10/25/human-readable-filesize-php
function human_filesize($bytes, $decimals = 2) {
    $size = array('B','kB','MB','GB','TB','PB','EB','ZB','YB');
    $factor = floor((strlen($bytes) - 1) / 3);
    return sprintf("%.{$decimals}f", $bytes / pow(1024, $factor)) . @$size[$factor];
}

echo human_filesize(filesize('example.zip'));

Even better

function MakeReadable($bytes) {
    $i = floor(log($bytes, 1024));
    return round($bytes / pow(1024, $i), [0,0,2,2,3][$i]).['B','kB','MB','GB','TB'][$i];
}

I modified @MrCaspan's method to address a few issues.

• It returns 0B instead of NANB when attempting to format 0 bytes, which was caused by a value of -INF calculated for the factor.
• I added petabytes, as I think this is the most reasonable max unit to display in most cases. If someone wanted a lower or higher ceiling, the units can easily be modified.
• When the factor was higher than the highest defined units, the function would just return an integer with no unit indication. This modified version just uses the highest defined unit when the factor exceeds the defined bounds.

It's a longer version for sure, but it's more readable and I think addressing the issues above warrants a lengthier function.

function readableBytes(int $bytes): string
{
    $unitDecimalsByFactor = [
        ['B', 0],
        ['kB', 0],
        ['MB', 2],
        ['GB', 2],
        ['TB', 3],
        ['PB', 3]
    ];

    $factor = $bytes ? floor(log($bytes, 1024)) : 0;
    $factor = min($factor, count($unitDecimalsByFactor) - 1);

    $value = round($bytes / pow(1024, $factor), $unitDecimalsByFactor[$factor][1]);
    $units = $unitDecimalsByFactor[$factor][0];

    return $value.$units;
}

If this function were to be adapted for use with larger factors, a type other than int would be required for the $bytes parameter due to its maximum value.

Another version, eliminates needless count() units will always be 5, ** operator, optional unit output, reworked array for determining decimals by the factor

function human_bytes(int $bytes, $u = false): string {
    if ($bytes < 1) return 0;

    $units = ['B', 'Kb', 'Mb', 'Gb', 'Tb', 'Pb'];
    $factor = min(floor(log($bytes, 1024)), 5);
    $value = round($bytes / (1024 ** $factor), $factor > 1 ? 2 : 0);

    return $u ? $value . $units[$factor] : $value;
}

Another version, eliminates needless count()

just FYI: count is "free" operation in php, cause array always have its size in internal structure.