Method
Uses the date’s ISO week Thursday to determine week and week-year.
Date & Time / browser tool
Week Number Calculator
Find the ISO week number and week-year for any calendar date.
A reliable way to label dates by their calendar week.
Your inputs stay on your device
Find the week number
live resultISO week
Dates use calendar rules in UTC. Workday calculations exclude Saturdays and Sundays, not public holidays.
Context & Reference
How it works
For reporting dates by ISO week.
utility guideHow to use it
Use this utility with your own values, then review the clearly labelled result and copy it when you need it elsewhere.
Understand the result
Week-year can differ from the calendar year near New Year.
Example
Check which ISO week contains January 1.
Practical tip
Use a valid calendar date.
Notes
This utility runs locally in this browser. Use a valid calendar date.
Useful next steps
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