PHP – Converting bytes to a readable format

function readable_filesize($bytes, $dp = 1) {
	// Extensions used
	$extensions = array('B', 'KB', 'MB', 'GB', 'TB', 'PB');
 
	foreach ($extensions as $ext) {
		// If we can't divide again without getting < 1
		if ($bytes < 1024) {
			return number_format($bytes, $dp).$ext;
		}
 
		$bytes /= 1024;
	}
 
	// If we're here, we're at the end of the extensions array
	// thus return what we have
	return $bytes.$ext;
}

echo readable_filesize(123456);