Days360 Calculates as Designed in Excel

ID: Q73210

The information in this article applies to:

Microsoft Excel for Windows, versions 3.x, 4.x, 5.0
Microsoft Excel for Windows 95, version 7.0
Microsoft Excel for the Macintosh, versions 3.x, 4.x, 5.0

SUMMARY

Microsoft Excel has a DAYS360 function, which is designed to calculate the number of days between two specified dates based on a 360-day year, instead of the normal 365-day year.

MORE INFORMATION

DAYS360 is based on twelve 30-day months and treats each month as such. This is useful to help compute payments if your accounting system is based on twelve 30-day months. So, when DAYS360 calculates the number of days between 2/28/91 and 3/1/91 as 3, this is correct. DAYS360 assumes that February has 30 days, not 28 (or 29 in a leap year). Likewise, DAYS360 treats the dates "1/30/91" and "1/31/91" identically. "1/31/91" is converted to "1/30/91".

DAYS360 does conform to the standards established by the NASD (National Association of Security Dealers), and the SIA standards which specify that:

if the start date is the 31st of a month, it is equal to the 30th of the same month

if the end date is the 31st of a month, it is equal to the 1st of the next month

except when the start date is the 30th of a month.

The European method of this function is more simple. The 31st of a month is always equal to the 30th of the same month.

DAYS360 calculates as designed and as described in the "Function Reference".

REFERENCES

Online Help, version 5.0
"Function Reference," version 4.0, 95-96
"Function Reference," version 3.0, page 46

Additional query words: 3.0 3.00 4.0 4.00 5.0


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Last Reviewed: March 21, 1999