Day of Week Calculator
Look up whether a civil date is Monday through Sunday. The answer is tied to the year-month-day you type, not to the clock on this device, so a late evening in one zone cannot flip the weekday to tomorrow.
How to use
- Enter the calendar date you care about — a wedding, a historical event, a future deadline.
- Read the weekday name. Invalid dates such as 31 April or 29 February in a common year are rejected.
- Use Days From Today if you need the date N days from a start, then come back here to name that weekday.
- Use Birthday Countdown if you only have a month and day and want the next occurrence from today.
How it works
Weekdays are a property of the Gregorian date, not of a Unix timestamp you happened to open at 23:00. This page parses year-month-day and reports the civil weekday for that date. It does not add your offset to “now,” and it does not guess which time zone the event “really” happened in. If you need the weekday of an instant on a timeline, convert the timestamp first on the Unix Timestamp page, then type the UTC or local calendar date you actually mean.
Leap days are ordinary dates when they exist. 29 February 2024 was a Thursday. 29 February 2023 is not a date and will not be accepted. Very early historical dates follow the proleptic Gregorian rules the browser can represent; they will not match every local calendar reform (Julian-to-Gregorian skips, tax-year New Year changes, and so on).
This is not a duration tool. It will not tell you how many Tuesdays fall between two dates, and it will not skip weekends. Business Days counts Mondays–Fridays in an inclusive range. Days Between Dates counts elapsed midnights. Day of Week answers the one-word question: what is the name of that day?
Planning uses are the usual ones: “what day is Christmas this year,” “was that invoice dated a Sunday,” “does the 31st fall on a Friday so the office is closed.” The lookup does not know holidays, opening hours or religious calendars. Pair it with Days From Today when you have an offset and want both the landing date and its weekday.
Time of day is not an input. Two events on the same civil date share a weekday here even if one was at 00:10 and the other at 23:50. For hours and minutes between clock times, use Time Duration.
Formula
Weekday = Gregorian calendar weekday of the given YYYY-MM-DD date
Worked examples
A known weekday
2024-01-31 → Wednesday
Leap day 2024
2024-02-29 → Thursday
Useful notes
- Calendar lookup only — not a duration and not a holiday calendar.
- Time zones do not change the weekday of the date you typed.
- Use Days From Today if you need a date N days away, then look up that weekday.
FAQ
- Does my time zone change the weekday?
No. The tool uses the calendar date you enter, not the current clock in your time zone.
- Does this work for dates in the past?
Yes, for Gregorian calendar dates the browser can represent. Very early historical dates may not match local calendar reforms.
- What about 29 February?
Leap days are valid. A non-leap 29 February is rejected as an invalid date.
- Can I see how many Mondays are in a range?
Not on this page. Look up each date, or use Business Days if you only need a Monday–Friday count.
- Does this use the Julian calendar?
No. It uses the Gregorian date the browser can represent. Early historical weekdays may not match contemporary local calendars.
Related tools
Days From Today
Find the exact calendar date a set number of days before or after a chosen start date.
Birthday Countdown
See the next birthday date, weekday and how many days remain from today.
Days Between Dates
Count how many calendar days separate two dates, including the week-and-remainder breakdown.
See all Date & Time tools.