The snippet below will return the number of week days between 2 dates also exclude any dates in an array such as bank holidays

gistfile1.php

<?php
function get_working_days($startDate,$endDate){

  $holidays = array(
			'2013-03-29',
			'2013-04-01',
			'2013-05-06',
			'2013-05-27',
			'2013-08-26',
			'2013-12-25',
			'2013-12-26',
			'2014-01-01',
			'2014-04-18',
			'2014-04-21',
			'2014-05-05',
			'2014-05-26',
			'2014-08-25',
			'2014-12-25',
			'2014-12-26',
			'2015-01-01',
			'2015-04-03',
			'2015-04-06',
			'2015-05-04',
			'2015-05-25',
			'2015-08-31',
			'2015-12-25',
			'2015-12-28',
			'2016-01-01',
			'2016-03-25',
			'2016-03-28',
			'2016-05-02',
			'2016-05-30',
			'2016-08-29',
			'2016-12-26',
			'2016-12-27',
			'2017-01-02',
			'2017-04-14',
			'2017-04-17',
			'2017-05-01',
			'2017-05-29',
			'2017-08-28',
			'2017-12-25',
			'2017-12-26',
			'2018-01-01',
			'2018-03-30',
			'2018-04-02',
			'2018-05-07',
			'2018-05-28',
			'2018-08-27',
			'2018-12-25',
			'2018-12-26',
			'2019-01-01',
			'2019-04-19',
			'2019-04-22',
			'2019-05-06',
			'2019-05-27',
			'2019-08-26',
			'2019-12-25',
			'2019-12-26',
			'2020-01-01',
			'2020-04-10',
			'2020-04-13',
			'2020-05-04',
			'2020-05-25',
			'2020-08-31',
			'2020-12-25',
			'2020-12-28'
		);

  $work = 0;
  $nowork = 0;
  $dayx = strtotime($startDate);
  $endx = strtotime($endDate);
  while($dayx <= $endx){
  	$day = date('N',$dayx);
   	$date = date('Y-m-d',$dayx);

   if($day > 5 || in_array($date,$holidays)){
   	$nowork++;
   } else $work++;
   	$dayx = strtotime($date.' +1 day');
  }
  return $work;
}

//usage example
echo get_working_days('2013-03-29','2013-04-15');

?>