Day of the Week Calculator
Find out what day of the week any date falls on, plus the ISO week number and day of the year.
Day of the week
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How to use it
- 1
Pick a date
Use the date picker to choose any day. Use the month and year dropdowns to jump to far-off dates.
- 2
Read the weekday
The large result shows the day of the week, from Monday through Sunday, for the date you chose.
- 3
Check the extra details
See the ISO week number, the day of the year, and the calendar quarter for that date.
Perfect for every need
Event & holiday planning
Find out which weekday a holiday or special date lands on before you make plans.
- What day is Christmas 2026
- New Year weekday
- Birthday day
Personal curiosity
Discover the day of the week you were born or another memorable date in your life.
- Day you were born
- Wedding day
- First day at work
Work & scheduling
Confirm the weekday for deadlines and delivery dates to avoid weekend surprises.
- Project deadlines
- Delivery dates
- Meeting days
Frequently asked questions
How does the calculator find the day of the week?
It uses the proleptic Gregorian calendar, the standard civil calendar, to determine the weekday for the exact date you select, whether it is in the past or the future.
What day of the week is Christmas 2026?
Pick December 25, 2026 in the date picker to see it instantly. The tool works for any date, so you can check any holiday in any year.
What is the ISO week number?
Under ISO 8601, weeks start on Monday and week 1 is the week containing the year's first Thursday. The tool shows both the week number and the week-numbering year.
What does day of the year mean?
It is the count of days from January 1. January 1 is day 1 and December 31 is day 365, or day 366 in a leap year.