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Find the day of week for any date. Shows weekday name, day-of-year, and leap year status. Uses proleptic Gregorian calendar.
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Finds the day of week for any date. Shows weekday name, day-of-year, ISO week number, and leap year status. Uses the proleptic Gregorian calendar (current calendar extended backward).
Day-of-week lookup is useful for historical research, scheduling, legal deadlines, and curiosity. The ISO week number is standard in European business contexts.
This tool is part of the DevStackIO platform — a collection of free online developer tools from DevStackIO. Browse more free developer resources on DevStackIO.
Historians, genealogists, event planners, legal professionals, students, and anyone asking 'what day was that?'
Enter a date (YYYY-MM-DD format or use the date picker)
The tool instantly shows weekday, day-of-year, ISO week, and leap year status
2024-07-041969-07-202000-01-01What calendar does this use?
Proleptic Gregorian (current rules extended to all dates).
What is ISO week?
Week 1 is the week with the year's first Thursday. Weeks start Monday.
Was July 20, 1969 a Sunday? Yes
the Moon landing was on a Sunday.
Authoritative specifications, standards, and in-depth reading for Day of Week Calculator.
Date
2024-07-04
Weekday
Thursday
Day of Year
186
ISO Week
28
Leap Year
Yes
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