How to add or subtract dates in Excel

How to add days with a date

We had already learned that a date value is stored internally as a date serial number in Excel. We can add days with a date using addition mathematical operator (+).

For example; 25-12-2021 + 3 = 28-12-2021 (add three days to the date 25-12-2021).

Following image shows dates are added with number of days and the result.

Above image shows a sample date, number of days to add (using addition mathematical operator (+)), date addition result, date serial number of the sample date, date serial number of the addition result and finally the difference between date serial numbers representing the sample date and the addition result.

From above image, you can see that Excel performs addition operation on date serial numbers, when we add days to a date.

How to subtract days with a date

Similar to addition of dates with days, we can subtract days from a date using subtraction mathematical operator (-).

For example; 25-12-2021 - 3 = 22-12-2021 (subtract three days from the date 25-12-2021).

Below image shows a sample date, number of days to subtract (using subtraction mathematical operator (+)), date subtraction result, date serial number of the sample date, date serial number of the subtraction result and then finally the difference between date serial numbers representing the sample date and the subtraction result.

From above image, you can see that Excel performs subtraction operation on date serial numbers, when we subtract days from a date.