The Excel WEEKNUM function takes a date and returns a week number (1-54) that corresponds to the week of year. The WEEKNUM function starts counting with the week that contains January 1. By default, weeks begin on Sunday.
- serial_num – A valid Excel date in serial number format.
- return_type – [optional] The day the week begins. Default is 1.
The WEEKNUM function starts counting with the week that contains January 1. Thereturn_type argument is optional and defaults to 1. Return_type can either be 1 or 2:
1 – Week begins on Sunday
2 – Week begins on Monday