Usage of the WEEKNUM() formula

Sometimes you may need to calculate how many weeks have passed in this year based on a date.

You can use this formula, WEEKNUM(Date,[return_type]), to calculate.

Date: Date field

Return_type: Optional. A number that determines on which day the week begins. The default is 1.

There are two systems used for this function:

System 1: The week containing January 1 is the first week of the year, and is numbered week 1.

System 2: The week containing the first Thursday of the year is the first week of the year, and is numbered as week 1. This system is the methodology specified in ISO 8601, which is commonly known as the European week numbering system.

If there are no specific requirements, it is recommended to use the System 1.

In the following table are all the return_types that you can use.

Example

Let's say we apply a formula that refers to A2, and the value in A2 is 2020/01/07. The result will be:

WEEKNUM(A2)  ->  2
WEEKNUM(A2, 13)  ->  1