DAYS360

Returns the number of days between two dates, using the 360 day year.

Syntax:

DAYS360(startdate, enddate, method)

startdate and enddate are the starting and ending dates (text or date-time serial numbers). If startdate is after the enddate, the result will be negative. method is an optional parameter; if 0 or omitted, the US National Association of Securities Dealers (NASD) method of calculation is used; if 1 (or <>0) the European method of calcuation is used. The calculation assumes that all months have 30 days, so a year (12 months) has 360 days.

Example:

DAYS360("2008-02-29", "2008-08-31")

returns 180, that is, 6 months of 30 days.

Application:

Calculating Loan Interest

Let's imagine you have a portfolio of business loans and you need to calculate the accrued interest for each loan. The loan terms specify that a 360-day year is used for interest calculations.

Table:

	Loan ID	Start Date	End Date	Principal	Annual Interest Rate	Days	Interest
	A	B	C	D	E	F	G
1	L-101	1/15/2025	3/15/2025	$50,000.00	5.50%	60	$458.33
2	L-102	1/31/2025	4/30/2025	$75,000.00	6.25%	90	$1,171.88
3	L-103	2/28/2025	5/1/2025	$100,000.00	4.80%	63	$840.00

To calculate the interest for each loan, you would first determine the number of days between the start and end dates using the DAYS360 function. The formula for calculating interest is:

Interest=Principal×Annual Interest Rate×(Number of Days/360)

Let's apply this to the data in the table. We'll use the default U.S. method for the DAYS360 function, which is often used in this type of calculation.

Loan L-101:

Start Date: 1/15/2025
End Date: 3/15/2025
Number of Days = DAYS360("1/15/2025", "3/15/2025") = 60 days
Interest = 50,000×5.50%×(60/360)=$458.33

Loan L-102:

Start Date: 1/31/2025
End Date: 4/30/2025
Number of Days = DAYS360("1/31/2025", "4/30/2025") = 90 days (The U.S. method treats the 31st as the 30th for the start date.)
Interest = 75,000×6.25%×(90/360)=$1,171.88

Loan L-103:

Start Date: 2/28/2025
End Date: 5/1/2025
Number of Days = DAYS360("2/28/2025", "5/1/2025") = 63 days (February is treated as a 30-day month, and the end date is May 1st).
Interest = 100,000×4.80%×(63/360)=$840.00