The Excel DAYS360 Function

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Related Function :

NETWORKDAYS Function

Basic Description

The Excel Days360 function returns the number of days between 2 dates, based on a 360-day year (12 x 30 months).

The format of the function is :

DAYS360( Start_date, End_date, [Method] )

where the arguments are as follows:

Start_date

The start of the period

End_date

The end of the period

[Method]

An optional logical argument, which gives the method to be used in the calculation. This can be either:

	FALSE (or omitted)	-	US (NASD) method used
or
	TRUE	-	European method used

US vs. European Method

US Method:

If start date is last day of month it is set to 30th of that month
If end date is last day of month, then:

If start date is last day of month the end date is set to the 1st of the following month
Otherwise, the end date is set to 30th of that month

European Method:

If start date is last day of month it is set to 30th of that month
If end date is last day of month, then it is set to 30th of that month

The financial day count basis rules are explained in more detail on the Wikipedia Day Count Convention page

Note that the Start_date and End_date arguments should be input as either:

References to cells containing dates

Dates returned from formulas

- If you attempt to input the Start_date and End_date as text, there is a chance that Excel may misinterpret this due to different date systems, or date interpretation settings.

Warning: Although you can input the dates as serial numbers, this is not recommended as the serial numbers may vary across different computer systems.

Examples

The spreadsheets below show simple examples of the Excel Days360 function. The format of the function is shown in the spreadsheet on the left and the results are shown in the spreadsheet on the right.

Formulas
Examples of use of the Excel Days360 Function

Results

In the above example :

In the function is cells B1 and B4 the Method argument has been omitted. Therefore, the US (NASD) method is used.
In cells B2, the Method is set to TRUE, so the European method is used. Note that this gives a different result from the function in cell B1, which uses the same two dates with the US (NASD) method.

Note also that, as recommended by Microsoft, in all four calls to the Days360 function, the Start_date and End_date arguments have been supplied as either cell references or the return values from functions (in the example the Excel Date function is used to supply the End_date argument to the function in cell B4).