# DAYS360 function

This article describes the formula syntax and usage of the DAYS360 function (function: A prewritten formula that takes a value or values, performs an operation, and returns a value or values. Use functions to simplify and shorten formulas on a worksheet, especially those that perform lengthy or complex calculations.) in Microsoft Office Excel.

## Description

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.

## Syntax

`DAYS360(start_date, end_date, [method])`

The DAYS360 function syntax has the following arguments (argument: A value that provides information to an action, an event, a method, a property, a function, or a procedure.):

• 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.

For more information, see Change the date system, format, or two-digit year interpretation.

• method    Optional. A logical value that specifies whether to use the U.S. or European method in the calculation.
Method Defined
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.
TRUE 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. Microsoft Excel for the Macintosh uses a different date system as its default.

For more information, see Change the date system, format, or two-digit year interpretation.

## Example

The example may be easier to understand if you copy it to a blank worksheet.

• Select the example in this article.

Important   Do not select the row or column headers.

Selecting an example from Help
• Press CTRL+C.
• In Excel, create a blank workbook or worksheet.
• In the worksheet, select cell A1, and press CTRL+V.

Important   For the example to work properly, you must paste it into cell A1 of the worksheet.

• 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.

After you copy the example to a blank worksheet, you can adapt it to suit your needs.

A B C
Dates
1/1/2008
1/30/2008
2/1/2008
12/31/2008
Formula Description Result
=DAYS360(A3,A4) Number of days between 1/30/2008 and 2/1/2008, based on a 360-day year. 1
=DAYS360(A2,A5) Number of days between 1/1/2008 and 12/31/2008, based on a 360-day year. 360
=DAYS360(A2,A4) Number of days between 1/1/2008 and 2/1/2008, based on a 360-day year. 30

Applies to:
Excel 2007