What Day of the Week Was That Date?
Find the day of the week for any date, past or future. Also shows ISO week number, day of year, quarter, and leap-year status.
Runs 100% in your browser — nothing is uploaded.
That date is a
Thursday
Thursday, 10 September 2026
- Day of year253
- ISO week37
- QuarterQ3
- Leap yearNo
- Days in month30
Frequently asked
Does this work for dates before 1970?
Yes — JavaScript Date handles dates from 271821 BC to 275760 AD. Historical dates before 1582 use the proleptic Gregorian calendar, which may differ from the Julian calendar in use at the time.
What is "ISO week"?
ISO 8601's week numbering: weeks start Monday, week 1 is the one containing the first Thursday of the year. Most European and international standards use this.
Is 2100 a leap year?
No — divisible by 100 but not 400, so it's not a leap year. 2000 was (divisible by 400). This bug tripped up many programs at the turn of the millennium.
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