Format bytes into a human readable format

formatFileSize.php

<?php
/**
 * Format the given file size in bytes to a human readable format.
 *
 * @param int $size The file size to format in bytes
 * @param int $precision The optional number of decimal digits to round to
 * @return string The formatted file size (e.g. "4.7G")
 */
function formatFileSize($size, $precision = 1)
{
	$units = array("B", "K", "M", "G", "T", "P", "E", "Z", "Y");

	$useUnit = null;

	foreach ($units as $index => $unit)
	{
		if ($size < 1024)
		{
			$useUnit = $unit;
			break;
		}

		$size /= 1024;
	}

	if ($useUnit == null)
	{
		$useUnit = end($units);
	}

	return round($size, $precision) . $useUnit;
}