Week Number Converter
Enter a date to find the week number of the year, or enter a week number to see its date range.
Date to Week Number
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Week Number to Dates
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How to use
- Enter your values in the boxes above or select an option.
- The result updates live right away — no button needed.
- Change a value or unit and the new result shows on its own.
Note
ISO 8601 standard: the week starts on Monday, and the first week of the year is the one that has the first Thursday of the year. Some years have 53 weeks.
Frequently Asked Questions (FAQ)
What does this week number calculator do?
Enter a date to find the week number of the year, or enter a year and ISO week number to see its full date range.
Which week standard is used?
ISO 8601: the week starts on Monday, and the first week of the year is the one with the first Thursday. Some years have 53 weeks.
Can a year have 53 weeks?
Yes. Under the ISO 8601 standard some years have 53 weeks instead of 52.
Do I need to press a button to convert?
No. The result updates live as you change the date or the week number.