Need formula to calculate workdays between dates & subtract 1. If no value, default to 0

Let's say A1 is the 'from date' and B1 is the 'to date'. I need a formula in C1 that will provide the number of the work days between A1 and B1 then subtract 1 day. Where there is no value in B1, I would like C1 to default to 0. Any ideas? Thanks in advance!

Try

=IF(B1="",0,NETWORKDAYS(A1,B1,Holidays)-1)

Where Holidays is an Optional range where you enter holiday dates that should be skipped.

it works! Thanks Jonmo1!

You're welcome.