Week Number Calculator
Enter any date to find out what ISO 8601 week of the year it falls in.
Week Number:
Enter a valid date to see the week number
How the ISO Week Number is Calculated
The ISO 8601 standard defines the week as starting on Monday. The first week of the year is the one that contains the first Thursday of the year, or equivalently, January 4th. This calculator uses that rule to compute the correct week number.