1] Add days directly If the expiry period is defined in days, you can calculate the expiry date by simply adding the number of days to the starting date using the + operator.

We show you how to use Excel to count days between two dates using the DAYS, DATEDIF, NETWORKDAYS, and TODAY functions, and Subtraction.

Excel makes it easy to find how many days there are between two dates. With a little more effort, you can find the number of days in which people will be actually working.

Bookkeepers, project managers, HR departments and more use the Excel Date & Time functions WEEKNUM, ISOWEEKNUM, WORKDAY, WORKDAY.INTL to calculate time. Here's how.