ISO Week Number Calculator
Get the ISO 8601 week number, weekday, and day-of-year for any date.
ISO week
2026-W31
Weekday
Wednesday
Day of year
210
Days remaining (year)
155
Weeks remaining (year)
21
About this tool
Type a date (or week + year) and see its ISO 8601 week number, weekday, day-of-year, week-of-year, and the Monday-anchored start/end dates. Useful for the r/excel 'WEEKNUM' threads and r/programming reporting-period confusion.
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