Quick Answer

COUPDAYS Function

Calculates the number of days in the coupon period that contains the settlement date.

Syntax

COUPDAYS

(settlement, maturity, frequency, [basis])

Parameters

Parameter	Description	Required
settlement	Date the security is purchased.	Required
maturity	Date the security expires.	Required
frequency	Number of coupon payments per year (1, 2, or 4).	Required
basis	Day-count convention (0 = US 30/360, default).	Optional

Basic Example

Days in the current coupon period

=COUPDAYS(DATE(2024,4,1), DATE(2034,4,1), 2)

ResultDays in coupon period

For a semi-annual bond, this typically returns 180 days under the 30/360 convention.

Advanced Examples

Example 1: Actual days in coupon period

Treasury bond

Use basis 1 for actual days

=COUPDAYS(DATE(2024,4,1), DATE(2034,4,1), 2, 1)

Result: Actual days in coupon period

Basis 1 counts the actual number of days in the period.

How COUPDAYS Works

COUPDAYS is used to determine the length of the coupon period, which is needed for accrued interest calculations.

1

Enter settlement

Type the settlement

2

Enter maturity

Type the maturity

3

Enter frequency

Type the frequency

4

Enter basis

Type the basis

5

Calculate

Press Enter to get the result.

Important Notes & Limitations

Frequency must be 1, 2, or 4.
Basis affects the day count.
Settlement must be before maturity.

Common Errors & Fixes

#NUM! errorInvalid dates, frequency, or basis.

Fix: Verify all inputs.

#VALUE! errorDates are not recognized.

Fix: Use DATE function or valid date serial numbers.

Download Practice File

Practice COUPDAYS with Real Data

Download a sample CSV file with pre-populated data and practice exercises for the COUPDAYS function. Works in both Excel and Google Sheets.

Works in Google SheetsCompatible with ExcelIncludes exercises

File format: CSV (comma-separated values) - opens in Excel, Google Sheets, and all spreadsheet apps

Related Functions

ACCRINT

Calculates accrued interest for a security that pays periodic interest.

ACCRINTM

Calculates accrued interest for a security that pays interest at maturity.

AMORDEGRC

Calculates depreciation for a specific period using the French declining balance method.

AMORLINC

Calculates depreciation for a specific period using the French straight-line method.

COUPDAYBS

Calculates the number of days from the beginning of the coupon period to the settlement date.

COUPDAYSNC

Calculates the number of days from the settlement date to the next coupon date.

Frequently Asked Questions

What is the difference between COUPDAYS and COUPDAYSNC?

COUPDAYS counts total days in the coupon period. COUPDAYSNC counts days from settlement to the next coupon.

Why does COUPDAYS return 180 for a semi-annual bond?

Under the 30/360 convention, each semi-annual period is assumed to have 180 days.