I've been doing some project planning using a Google Spreadsheet and came across a couple of useful functions when dealing with dates.
DAYS360(date_1, date_2, type) returns the difference between two dates, for example =DAYS360(A1, A2).
NETWORKDAYS(start_date, end_date, holidays) calculates the number of working days between two dates. You can also subtract holidays by passing a range of dates as a third parameter, for example =NETWORKDAYS(A1, A2, Holidays!A1:A30)
DAYS360(date_1, date_2, type) returns the difference between two dates, for example =DAYS360(A1, A2).
NETWORKDAYS(start_date, end_date, holidays) calculates the number of working days between two dates. You can also subtract holidays by passing a range of dates as a third parameter, for example =NETWORKDAYS(A1, A2, Holidays!A1:A30)