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Excel tips and tricks

Adding months and years to a date

In Microsoft Excel, you can add days to dates by entering a formula. To add 10 days to a date, the formula should be =date+10. Figure 1 shows three ways to add 10 days to a date. In column C, the formula is used to calculate the result in column B.

Adding 10 days to a date
Figure 1 Adding 10 days to a date

A problem can occur when we want to add several months or years to a date. To add 3 months, we might use =date+90, counting 90 days. Months do not have the same number of days, so this does not add exactly 3 months. The example is shown in Figure 2.

Adding 90 days to a date
Figure 2 Adding 90 days to a date

To add exactly 3 months, we need these functions:

  • YEAR - extracts the year from a date. =YEAR(A1) returns 2016.
  • MONTH - extracts the month from a date. =MONTH(A1) returns 4.
  • DAY - extracts the day from a date. =DAY(A1) returns 7.
  • DATE - builds a date from year, month and day numbers. =DATE(2016;4;7) returns 7.4.2016. Extra months or days are carried over, for example =DATE(2010;42;1) -> 1.6.2013.

The functions YEAR, MONTH, DAY have 1 argument, the date. DATE has 3 arguments: =DATE(year;month;day).

Figure 3 shows the formula for adding exactly 3 months.

Adding 3 months to a date
Figure 3 Adding exactly 3 months to a date

YEAR, MONTH and DAY split the date, so you can add months: =DATE(YEAR(B2);MONTH(B2)+3;DAY(B2)).

For years, you could use =date+365*numberOfYears, but it is better to use =DATE(YEAR(A2)+10;MONTH(A2);DAY(A2)).

With the date 1.1.2016 in A2, the formula returns 1.1.2026.