This article describes the formula syntax and usage of the COUPDAYS 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 Excel.
Description
Returns the number of days in the coupon period that contains the settlement date.
Syntax
COUPDAYS(settlement, maturity, frequency, [basis])
Important Dates should be entered by using the DATE function, or as results of other formulas or functions. For example, use DATE(2008,5,23) for the 23rd day of May, 2008. Problems can occur if dates are entered as text.
The COUPDAYS 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.):
 Settlement Required. The security's settlement date. The security settlement date is the date after the issue date when the security is traded to the buyer.
 Maturity Required. The security's maturity date. The maturity date is the date when the security expires.
 Frequency Required. The number of coupon payments per year. For annual payments, frequency = 1; for semiannual, frequency = 2; for quarterly, frequency = 4.
 Basis Optional. The type of day count basis to use.
Basis 
Day count basis 
0 or omitted 
US (NASD) 30/360 
1 
Actual/actual 
2 
Actual/360 
3 
Actual/365 
4 
European 30/360 
Remarks
 Microsoft Excel stores dates as sequential serial numbers so 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 39,448 days after January 1, 1900.
 The settlement date is the date a buyer purchases a coupon, such as a bond. The maturity date is the date when a coupon expires. For example, suppose a 30year bond is issued on January 1, 2008, and is purchased by a buyer six months later. The issue date would be January 1, 2008, the settlement date would be July 1, 2008, and the maturity date is January 1, 2038, 30 years after the January 1, 2008 issue date.
 All arguments are truncated to integers.
 If settlement or maturity is not a valid date, COUPDAYS returns the #VALUE! error value.
 If frequency is any number other than 1, 2, or 4, COUPDAYS returns the #NUM! error value.
 If basis < 0 or if basis > 4, COUPDAYS returns the #NUM! error value.
 If settlement ≥ maturity, COUPDAYS returns the #NUM! error value.
Example
The example may be easier to understand if you copy it to a blank worksheet.
How do I copy an example?
 Select the example in this article. If you are copying the example in Excel Online, copy and paste one cell at a time.
Important: Do not select the row or column headers.
Selecting an example from Help
 Press CTRL+C.
 Create a blank workbook or worksheet.
 In the worksheet, select cell A1, and press CTRL+V. If you are working in Excel Online, repeat copying and pasting for each cell in the example.
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 
Data 
Description 
January 25, 2007 
Settlement date 
November 15, 2008 
Maturity date 
2 
Semiannual coupon (see above) 
1 
Actual/actual basis (see above) 
Formula 
Description (Result) 
=COUPDAYS(A2,A3,A4,A5) 
The number of days in the coupon period that contains the settlement date, for a bond with the above terms (181) 

Note In Excel Online, to view the result in its proper format, select the cell, and then on the Home tab, in the Number group, click the arrow next to Number Format, and click General.