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The Excel DAYS360 Function

Related Functions:
DAYS
NETWORKDAYS

Function Description

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

The syntax 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
TRUE - European method used

US vs. European Method

US Method:

  • If the start date is last day of a month it is set to the 30th of that month;
  • If the end date is last day of month, then:
  • If the start date is the last day of month, the end date is set to the 1st of the following month;
  • Otherwise, the end date is set to the 30th of that month.

European Method:

  • If the start date is the last day of the month it is set to the 30th of that month;
  • If the end date is the last day of the month, then it is set to the 30th of that month.
The financial day count basis rules are explained in detail on the Wikipedia Day Count Convention page

Date Arguments

It is advised that the start_date and end_date arguments should be input to the Days360 function as either:

or

This is because there is a risk that date arguments that are supplied to Excel functions as text representations of dates may be misinterpreted, depending on the date systems and date interpretation settings on your computer.


Excel Days360 Function Examples

The spreadsheet below shows four simple examples of the Excel Days360 function.

 Formulas:
  A B
1 01-Jan-2015 =DAYS360( A1, A2 )
2 31-Jan-2015 =DAYS360( A1, A2, TRUE )
3 01-Feb-2015 =DAYS360( A1, A3, FALSE )
4   =DAYS360( A3, DATE( 2015, 2, 2 ) )
 Results:
  A B
1 01-Jan-2015 30
2 31-Jan-2015 29
3 01-Feb-2015 30
4   1

In the above examples:

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 as values returned from functions (in cell B4, the Date function is used to supply the end_date argument).


For further information and examples of the Excel DAYS360 function, see the Microsoft Office website.


DAYS360 Function Errors

If you get an error from the Excel Days360 function, this is likely to be one of the following:

Common Errors
#NUM! - Occurs if either of the supplied start_date or end_date arguments are numeric values, but are not recognised as valid dates.
#VALUE! -

Occurs if either:

  • One or both of the supplied start_date or end_date arguments are text values that can not be interpreted as dates.
  • The supplied [method] argument is non-numeric.
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