WEEKNUM function

The WEEKNUM function in Excel is used to determine the week number of a given date. It helps you find out which week of the year a particular date falls in. This function can be especially useful in various scheduling and date-related tasks.

Syntax

WEEKNUM(serial_number, [return_type])

Arguments

serial_number	The date for which you want to find the week number. It can be entered as a date in a recognized format, a reference to a cell containing a date, or a formula that results in a date.
[return_type]	A number that specifies which day of the week is considered the first day of the week. This argument can take on values from 1 to 21, with different values representing different systems for determining the first day of the week. The default is 1, where Sunday is considered the first day.

How to Use

The WEEKNUM function is relatively simple to use. You provide it with a date, and it returns the week number for that date. Here’s the basic usage:

Let’s look at a few examples:

Example 1:

If you want to find the week number for a date in cell A1, where Sunday is considered the first day of the week, you can use the following formula:

This formula will return the week number for the date in cell A1 according to the system where Sunday is the first day of the week.

Example 2:

If you have a date like “2023-11-03” and want to find the week number, you can directly enter the date in the formula:

This formula will return the week number for the given date, considering Sunday as the first day of the week.

Example 3:

If you don’t specify the return_type argument, it defaults to 1 (Sunday as the first day of the week). So, you can simply use the formula like this:

It will return the week number with Sunday as the first day.

Additional Information

The WEEKNUM function is versatile and can be helpful in various situations where you need to work with date-related data. Remember that the [return_type] argument is optional and can be adjusted according to your specific needs.

If you want to learn more about the [return_type] values and how they affect the result, you can check the official Microsoft Excel documentation or other reliable sources for a detailed explanation.