The WORKDAY function calculates a workday that is 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 you want to exclude from the count of workdays.
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 between two days and exclude days specified as weekends.
NETWORKDAYS – Calculate the number of working days 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. If you used the 35th day of November, “11/35/2018”, this error could happen.
#VALUE! – The inputs don’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.
Consider using the IMPORTXML function to obtain a list of your local holidays from the web.