Contents

# ISOWEEKNUM

ISOWEEKNUM calculates the week number of the year for the internal date value.

The International Standard ISO 8601 has decreed that Monday shall be the first day of the week. A week that lies partly in one year and partly in another is assigned a number in the year in which most of its days lie. That means that week number 1 of any year is the week that contains the January 4th.

This function is available since LibreOffice 5.1.

This function is part of the Open Document Format for Office Applications (OpenDocument) standard Version 1.2. (ISO/IEC 26300:2-2015)

### Syntax

ISOWEEKNUM(Number)

Number is the internal date number.

When entering dates as part of formulas, slashes or dashes used as date separators are interpreted as arithmetic operators. Therefore, dates entered in this format are not recognized as dates and result in erroneous calculations. To keep dates from being interpreted as parts of formulas use the DATE function, for example, DATE(1954;7;20), or place the date in quotation marks and use the ISO 8601 notation, for example, "1954-07-20". Avoid using locale dependent date formats such as "07/20/54", the calculation may produce errors if the document is loaded under different locale settings.

Unambiguous conversion is possible for ISO 8601 dates and times in their extended formats with separators. If a #VALUE! error occurs, then unselect Generate #VALUE! error in LibreOffice - Preferences Tools - Options - LibreOffice Calc - Formula, button Details... in section "Detailed Calculation Settings", Conversion from text to number list box.

### Primjeri

=ISOWEEKNUM(DATE(1995;1;1)) returns 52. Week 1 starts on Monday, 1995-01-02.

=ISOWEEKNUM(DATE(1999;1;1)) returns 53. Week 1 starts on Monday, 1999-01-04.

Related Topics

ISOWEEKNUM wiki page.

Date & Time Functions

DATE

DATEDIF

DATEVALUE

DAY

DAYS

DAYS360

DAYSINMONTH

DAYSINYEAR

EASTERSUNDAY

EDATE

EOMONTH

HOUR

ISLEAPYEAR

ISOWEEKNUM

MINUTE

MONTH

MONTHS

NETWORKDAYS

NETWORKDAYS.INTL

NOW

SECOND

TIME

TIMEVALUE

TODAY

WEEKDAY

WEEKNUM

WEEKNUM_EXCEL2003

WEEKNUM_OOO

WEEKS

WEEKSINYEAR

WORKDAY

WORKDAY.INTL

YEAR

YEARFRAC

YEARS

Please support us!