public function getRealFileSize($fileSize)
    {
        //B goes at the end because it's always matched otherwise
        $validUnits = ['KB', 'MB', 'GB', 'TB'];
        $value = str_replace(' ', '', $fileSize);

        $pattern = '/\d+/';
        preg_match($pattern, $value, $match);

        foreach ($validUnits as $unit) {
            if (strpos($fileSize, $unit)) {
                switch ($unit) {
                    case 'B':
                        return $match[0] * pow(1024, 0);
                    case 'KB':
                        return $match[0] * pow(1024, 1);
                    case 'MB':
                        return $match[0] * pow(1024, 2);
                    case 'GB':
                        return $match[0] * pow(1024, 3);
                    case 'TB':
                        return $match[0] * pow(1024, 4);
                }
            }
        }

        return $fileSize;
    }