WEEKNUM Function
The WEEKNUM function is one of the date and time functions. It used to return the number of the week the specified date falls within the year.
Syntax
WEEKNUM(serial_number, [return_type])
The WEEKNUM function has the following arguments:
| Argument |
Description |
| serial_number |
A number representing the date within the week, entered using the DATE function or other date and time function. |
| return_type |
A numeric value used to determine on which day the week begins. The possible values are listed in the table below. |
The return_type argument can be one of the following:
| Numeric value |
Week begins on |
System |
| 1 or omitted |
Sunday |
1 |
| 2 |
Monday |
1 |
| 11 |
Monday |
1 |
| 12 |
Tuesday |
1 |
| 13 |
Wednesday |
1 |
| 14 |
Thursday |
1 |
| 15 |
Friday |
1 |
| 16 |
Saturday |
1 |
| 17 |
Sunday |
1 |
| 21 |
Monday |
2 |
Notes
When return_type is set to 1-17, System 1 is used. This means that the first week in a year is the week that contains January 1.
When return_type is set to 21, System 2 is used. This means that the first week in a year is the week that contains the first Thursday of the year. System 2 is commonly used in Europe according to the ISO 8601 standard.
How to apply the WEEKNUM function.
Examples
The figure below displays the result returned by the WEEKNUM function.
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