WEEKNUM

The WEEKNUM function returns the week number of a specific date.

Syntax

=WEEKNUM(serial_number, [return_type])

Parameters

• serial_number: The date for which you want to determine the week number
• return_type: Optional. A number that determines which week numbering system to use:
  • 1 (default): Week 1 starts on Sunday
  • 2: Week 1 starts on Monday

Examples

=WEEKNUM("2025-04-21") // Returns the week number (Sunday start)
=WEEKNUM("2025-04-21", 2) // Returns the week number (Monday start)
=WEEKNUM(TODAY()) // Returns the week number for current date