Returns the number of the ISO (International Organization for Standardization) week of the year where the provided date falls.
Sample Usage
ISOWEEKNUM(DATE(1969, 7, 20))
ISOWEEKNUM("6/14/2002")
Syntax
ISOWEEKNUM(date)
date
- The date for which to determine the ISO week number. Must refer to a cell containing a date, number, or function returning a date type.
Notes
- When entering the date, use the
DATE
function, as text values might return errors. - Per the European system for numbering weeks (also known as ISO 8601):
- Weeks begin on Monday and end on Sunday.
- Week 1 of the year is the week containing the first Thursday of the year.
- As a result, if the first Thursday is after January 4, at least one of the following days, January 1-3, will have an
ISOWEEKNUM
of 52 or 53. - Similarly, if the first Thursday is before January 4, at least one of the following days, December 29-31, will have an
ISOWEEKNUM
of 1. - If the first Thursday is January 4, December 29-31 of the previous year will have
ISOWEEKNUM
of 52 and January 1-7 of the current year will haveISOWEEKNUM
of 1.
- As a result, if the first Thursday is after January 4, at least one of the following days, January 1-3, will have an
See Also
WEEKNUM
: Returns a number representing the week of the year where the provided date falls.WEEKDAY
: Returns a number representing the day of the week of the date provided.DAYS360
: Returns the difference between two days based on the 360-day year used in some financial interest calculations.DATE
: Converts a year, month, and day into a date.DATEVALUE:
Converts a provided date string in a known format to a date value.