DAYS360 function

This article describes the formula syntax and usage of the DAYS360function in Microsoft Excel.


The DAYS360 function returns the number of days between two dates based on a 360-day year (twelve 30-day months), which is used in some accounting calculations. Use this function to help compute payments if your accounting system is based on twelve 30-day months.



The DAYS360 function syntax has the following arguments:

  • Start_date, end_date    Required. The two dates between which you want to know the number of days. If start_date occurs after end_date, the DAYS360 function returns a negative number. Dates should be entered by using the DATE function, or derived from the results of other formulas or functions. For example, use DATE(2008,5,23) to return the 23rd day of May, 2008. Problems can occur if dates are entered as text.

  • Method    Optional. A logical value that specifies whether to use the U.S. or European method in the calculation.



FALSE or omitted

U.S. (NASD) method. If the starting date is the last day of a month, it becomes equal to the 30th day of the same month. If the ending date is the last day of a month and the starting date is earlier than the 30th day of a month, the ending date becomes equal to the 1st day of the next month; otherwise the ending date becomes equal to the 30th day of the same month.


European method. Starting dates and ending dates that occur on the 31st day of a month become equal to the 30th day of the same month.

Note   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, 2008 is serial number 39448 because it is 39,447 days after January 1, 1900.


Use the embedded workbook shown here to work with examples of this function. You can inspect and change existing formulas, enter your own formulas, and read further information about how the function works.


To work in-depth with this workbook, you can download it to your computer and open it in Excel. For more information, see the article Download an embedded workbook from OneDrive and open it on your computer.

Applies To: Excel 2010, Excel Starter, Excel Online, SharePoint Online

Was this information helpful?

Yes No

How can we improve it?

255 characters remaining

To protect your privacy, please do not include contact information in your feedback. Review our privacy policy.

Thank you for your feedback!

Support resources

Change language