dolphin/single-functions/folder-size.php

<?php
/**
 *  dolphin. Collection of useful PHP skeletons.
 *  Copyright (C) 2019  Johannes 'Banana' Keßler
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the COMMON DEVELOPMENT AND DISTRIBUTION LICENSE
 *
 * You should have received a copy of the
 * COMMON DEVELOPMENT AND DISTRIBUTION LICENSE (CDDL) Version 1.0
 * along with this program.  If not, see http://www.sun.com/cddl/cddl.html
 */

/**
 * Simple functon to get the size of a folder
 * ignores . files and does not really work well with large files
 *
 * @param string $folder Absolute path to folder
 */
function folderSize($folder) {
	$ret = 0;

	if(file_exists($folder) && is_readable($folder)) {
		foreach (glob(rtrim($folder, '/') . '/*', GLOB_NOSORT) as $each) {
			$ret += is_file($each) ? filesize($each) : folderSize($each);
		}
	}

	return $ret;
}