Date & Time
Week Number Calculator
Find the ISO week number for any date. Useful for project planning, reporting, and scheduling.
Week Number
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How It Works
The calculator uses the ISO 8601 standard to determine the week number. Weeks start on Monday and the first week contains January 4th.
Example
July 7, 2024 falls in week 28 of the year.
Frequently Asked Questions
What is an ISO week?
ISO 8601 is an international standard where weeks start on Monday and the first week contains January 4th.
Does the week number reset on January 1?
Not always. Sometimes the first few days of January belong to week 52 or 53 of the previous year.
What's the maximum week number?
Most years have 52 weeks, but years starting on Thursday or leap years starting on Wednesday can have 53 weeks.