# ISOWEEKNUM

## Rational

Find the ISO week number of a year for a given date.

## Description

The Excel ISOWEEKNUM function return ISO week number considering a week begins on Monday. Example; to find ISO week number for any date (09-03-2017), use = ISOWEEKNUM(date) that returns 10.

Under ISO week date system, the first week starts on Monday of the calendar year with a Thursday.

## Syntax

=ISOWEEKNUM(date)

## Parameters

date – A valid argument of date or serial number recognized by Excel

## Return Value

An Integer between 1 and 52 or 53 representing week number of a specific date as per ISO standard.

## Key Notes

• Excel ISOWEEKNUM function categorize dates by the week number of the year based on ISO date standards.
• Make sure to use the date as a cell reference rather than inputting it manually.
• Use the WEEKNUM function to returns the normal week number in the year.

### WEEKNUM

The WEEKNUM function finds the week number of date and week start day, i.e., week starting from Monday (05-06-2018-C7), use =WEEKNUM(B7,2) that returns ‘23’.

### WEEKDAY

The WEEKDAY function returns an integer between 1 and 7 the corresponds specific day of a week. Example; (07-04-2018: Cell-B6), use =WEEKDAY(B6,2) returns ‘6’.

### DAY

The DAY function returns an integer value that represents the day element of a date. I.e.; to extract day component, use =DAY(“08-08-2017”) that returns ‘8’.