# The Excel COUPDAYS Function

Related Functions:
COUPDAYBS
COUPDAYSNC

## Basic Description

The Excel COUPDAYS function calculates the number of days in a coupon period that contains the settlement date.

The syntax of the function is :

COUPDAYS( settlement, maturity, frequency, [basis] )

Where the arguments are as follows:

settlement-The security's settlement date
maturity-The security's maturity date
frequency-

The number of coupon payments per year. This must have one of the following values:

 1 - Annually 2 - Semi-Annually 4 - Quarterly
[basis]-An optional argument which defines the day count basis to be used in the calculation.
This may have any of the following values :
BasisDay Count Basis
0 (or omitted)US (NASD) 30/360
1actual/actual
2actual/360
3actual/365
4European 30/360
A detailed explanation of the financial day count basis rules is provided on the Wikipedia Day Count Convention page

As the settlement and maturity arguments are dates, these should be input to the function as either:

• References to cells containing dates
or
• Date values returned from formulas

- If you attempt to input these dates as text, it is possible that they may be misinterpreted, due to different date systems, or date interpretation settings on your computer.

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

## Excel Coupdays Function Example

Cell A3 of the spreadsheet below shows the Excel Coupdays function, used to calculate the number of days in the period containing the settlement date, for a security that has the settlement date 01-Jan-2011, maturity date 25-Oct-2012, and 4 payments per year. The US (NASD) 30/360 day count basis is used.

The spreadsheet on the left shows the format of the function and the spreadsheet on the right shows the function result.

Formulas:
A
101-Jan-2011
225-Oct-2012
3=COUPDAYS( A1, A2, 4 )
Results:
A
101-Jan-2011
225-Oct-2012
390

Note that, in the above example :

• As recommended, the settlement and maturity date arguments have been supplied to the function as references to cells containing dates
• The [basis] argument has been omitted from the function. Therefore, the function uses the default value 0 (denoting the US (NADS) 30/360 day count basis)

More details and examples of the Excel Coupdays function are provided on the Microsoft Office website.

## Coupdays Function Errors

If you get an error from the Excel Coupdays Function, this is most likely to be one of the following:

Common Errors
 #VALUE! - Occurs if either:the supplied settlement or the supplied maturity date is not a valid Excel datethe supplied frequency or the supplied [basis] argument is non-numeric #NUM! - Occurs if either:the supplied settlement date is ≥ maturity datethe supplied frequency argument is a number that is not equal to 1, 2 or 4the supplied [basis] argument is a number that is not equal to 0, 1, 2, 3 or 4 #NAME? - Occurs when Analysis ToolPak add-in is not enabled in your Excel.You will need to enable the add-in if you want to use the Excel Coupdays function.