Suppose you want to adjust a project's schedule date by adding two weeks to see what the new completion date will be or you want to determine how long a single activity will take to complete in a list of project tasks. You can add or subtract a number of days to or from a date by using a simple formula, or you can use worksheet functions designed to work with dates in Excel.

Add days to or subtract days from a date

Suppose that an account balance of yours is due on February 8, 2015. You want to transfer funds to your checking account so that those funds arrive 15 calendar days before that date. In addition, you know that your account has a 30 day billing cycle and you want to determine when you should transfer funds for your March 2015 bill so that those funds are available 15 days before that date.

1. In cell A1, type 2/8/15.

2. In cell B1, type =A1-15.

3. In cell C1, type =A1+30.

4. In cell D1, type =C1-15.

Cells A1 and C1 show the due dates (2/08/15 and 3/10/15) for the February and March account balances, and cells B1 and D1 show the dates (1/24/15 and 2/23/15) by which you should transfer your funds for those due dates.

Add months to or subtract months from a date

You can use the EDATE function function to quickly add or subtract a specific number of whole months to or from a date.

The EDATE function requires two values (also referred to as arguments): the start date and the number of months that you want to add or subtract. To subtract months, enter a negative number as the second argument (for example, =EDATE("2/15/15",-5). This formula results in the date 9/15/14.

You can specify the value of the start date either by referring to a cell that contains a date value or by entering a date enclosed in quotation marks, such as "2/15/15".

For example, suppose you want to add 16 months to October 16, 2014.

1. In cell A5, type 10/16/14.

2. In cell B5, type =EDATE(A5,16).

The function uses the value in cell A5 as the date.

3. In cell C5, type =EDATE("10/16/14",16).

In this case, the function uses a date value that you enter directly, "10/16/14".

Cells B5 and C5 should both show the date 2/16/16.

Note: Depending on the format of the cells that contain the formulas that you entered, Excel might display the results as serial numbers; in this case, 2/16/16 might be displayed as 42416.

Excel stores dates as sequential serial numbers so that they can be used in calculations. By default, January 1, 1900 is serial number 1, and January 1, 2010 is serial number 40179 because it is 40,178 days after January 1, 1900.

4. If your results appear as serial numbers, select cells B5 and C5, and then continue with the following steps.

5. On the Home tab, in the Cells group, click Format, and then click Format Cells.

6. In the Format Cells dialog box, click the Number tab.

7. Under Category, click Date, and then click OK.
The value in each of the cells should appear as a date instead of a serial number.

Add years to or subtract years from a date

Example

To use this example in Excel, copy the data in the table below, and paste it in cell A1 of a new worksheet.

 Date Years to add (or subtract) 6/9/2014 3 9/2/2014 -5 12/10/2015 25 Formula Description (Result) =DATE(YEAR(A2)+B2,MONTH(A2),DAY(A2)) Adds 3 years to 6/9/2014 (6/9/2017) =DATE(YEAR(A3)+B3,MONTH(A3),DAY(A3)) Subtracts 5 years from 9/2/2014 (9/2/2009) =DATE(YEAR(A4)+B4,MONTH(A4),DAY(A4)) Adds 25 years to 12/10/2014 (12/10/2039)

To switch between viewing the results and viewing the formulas that return the results, press Ctrl+` (grave accent), or on the Formulas tab, in the Formula Auditing group, click the Show Formulas button.

How the formula works

In each of the three formulas, a specified number of years from column B is added to the year value that is derived from the date in column A.

For example, in cell A7, the YEAR function is used on the date in cell A3 (6/9/2014) and returns 2014 as the year. The formula then adds 3 (the value in cell B3) to the year value, which results in 2017. In the same formula, the MONTH function returns the value 6 and the DAY function returns the value 9. The DATE function then combines these three values into a date that is three years in the future — 6/9/2017.

You can use a similar formula to add months to a date. For example, by using the previous sample data, you can add 9 months to the date 6/9/2014 by using the following formula: =DATE(YEAR(A2),MONTH(A2)+9,DAY(A2)). This formula returns the date 3/9/2015.

Add a combination of days, months, and years to a date

Example

To use this example in Excel, copy the data in the table below, and paste it in cell A1 of a new worksheet.

 Date 6/9/2020 Formula Description (Result) =DATE(YEAR(A2)+3,MONTH(A2)+1,DAY(A2)+5) Add 3 years, 1 month, and 5 days to 6/9/2020 (7/14/2023) =DATE(YEAR(A2)+1,MONTH(A2)+7,DAY(A2)+5) Add 1 year, 7 months, and 5 days to 6/9/2020 (1/14/2022)

To switch between viewing the results and viewing the formulas that return the results, press Ctrl+` (grave accent), or on the Formulas tab, in the Formula Auditing group, click the Show Formulas button.

The formulas in the example have the following arguments (an argument is a value that is supplied to a function).

start_date: A date or reference to a cell that contains a date.

How the formula works

In each of the formulas, a specified number of years, months, and days are added to the date that is contained in cell A3.

For example, in cell A6 (the second formula), the YEAR function is used on the date in cell A3 (6/9/2020) and returns 2020 as the year. The formula then adds 1 to the year value, which results in 2021. The MONTH function returns the value 6 (June), and 7 months are added to that value. Because the total of 6 months plus 7 months is 13 months, the DATE function adds 1 year to the year value, resulting in 2022. The DATE function then subtracts 12 from the month value, resulting in a value of 1 for the month. The DAY function returns the value 9, and 5 days are added to that, resulting in 14. Finally, the DATE function combines these three values (2022, 1, and 14) into a date that is one year, seven months, and 5 days in the future — 1/14/2022.

Share