The WORKDAY function calculates a workday a given number of days away from a date. You can optionally specify a list of holidays to exclude from the count. If your days, months, and years are in different cells, use the DATE function to combine them.
start_date– The date from which to start counting the days.
days– The number of days to add to the start_date
[holidays]– Optional specification of which days are to be excluded from the count of work days.
WEEKDAY – Returns the week number for a given date.
DAYS – Find the number of days between two dates.
NETWORKDAYS.INTL – Calculate the number of working days in between two days and exclude specified days as weekends.
NETWORKDAYS – Calculate the number of working days in between two days and exclude weekends.
WORKDAY.INTL – Like this function but with movable weekends.
#NUM – The inputs are numbers but are not valid dates. This could happen if you used the 35th day of November, “11/35/2018”.
#VALUE! – The inputs are something that doesn’t convert to a number such as “The other day” or “Yester-yester-day”.
Live examples in Sheets
Go to this spreadsheet for the examples of the WORKDAY function that you can study and use anywhere you would like.