Calculate working hours excl weekends and holidays

[TriffyBoo]

I need to calculate the number of working hours between two dates excluding weekends and bank holidays.
I found the following formula online somewhere and thought it was working brilliantly, but it doesn't seem to be excluding Saturdays

(NETWORKDAYS.INTL(STARTDT,ENDDT,11,Holidays)-1)*("17:00"-"8:30")+IF(NETWORKDAYS.INTL(ENDDT,ENDDT,11,Holidays),MEDIAN(MOD(ENDDT,1),"8:30","17:00"),"17:00")-MEDIAN(NETWORKDAYS.INTL(ENDDT,ENDDT,11,Holidays)*MOD(STARTDT,1),"8:30","17:00"))

The holidays is from a range of cells elsewhere on the sheet e.g Z1:Z15

I am not great with excel, can copy formulas but I don't necessarily understand them, so please keep it as simple as possible!!

Please can anyone help me?

 

[steve the fish]

I wasn't familiar with the formula but looking you need to change the 11 you have there to a 1. Or use networkdays which is fixed mon-fri.

 

[TriffyBoo]

Thanks so much - that's the problem with just copying and pasting without understanding how it works!