What day of the week was a date?
Enter any date and this tool tells you which day of the week it fell on. It uses the calendar that was actually in force at the time, so dates before the Gregorian reform are given on the Julian calendar the way contemporary records wrote them.
Result
October 23, 2026 was a Friday.
- Day of the week
- Friday
- Calendar used
- Gregorian
- Day of the year
- 296th of 365
- Week
- ISO week 43 of 2026 · Q4
- Week of the month
- 4th
- Leap year
- No — 365 days
- That day in history
- What happened on October 23
How it is calculated
- The date is converted to a Julian Day Number — a running count of days used by astronomers — and the weekday is the remainder when that count is divided by seven. No lookup tables, no leap-year special cases.
- Dates from 15 October 1582 use the Gregorian calendar (leap years every four years, except century years not divisible by 400).
- Dates before 15 October 1582 use the Julian calendar (a leap year every four years with no exception), which is how they were recorded at the time.
- The day-of-year, ISO week number and quarter come from the same day count, so every figure on the page agrees.
Where this is used in the real world
- Genealogy: matching a birth, marriage or burial record to the day of the week named in a parish register.
- Contracts and deadlines: checking whether a historical date fell on a weekend or a business day.
- Writing and research: getting the weekday right in a novel, article or documentary set in the past.
- Curiosity: finding out what day of the week you were born on.
Good to know
- Britain and its colonies, including America, kept the Julian calendar until 14 September 1752, and Russia until 1918. A date recorded locally in those places can differ from the same moment in Catholic Europe by 10 to 13 days.
- Years before 1 CE use the astronomical convention where year 0 exists; historical sources that write “1 BCE” mean year 0 here.
- The week numbers follow ISO 8601, where a week starts on Monday and week 1 is the week containing the first Thursday of the year. Some countries number weeks differently.
Questions people ask
What day of the week was I born on?
Enter your birth date above. The weekday shown is the one printed on a calendar for that year, worked out from the day count rather than from a lookup table.
Why does the answer say “Julian calendar”?
For dates before 15 October 1582 the Gregorian calendar did not exist yet. The tool shows the weekday as it was reckoned at the time, and also shows what the same date would be under Gregorian rules for comparison.
Does this work for future dates?
Yes. The Gregorian calendar is defined indefinitely into the future, so a date in 2099 has a definite weekday.
Is 29 February handled correctly?
Yes. Leap years are applied by the rule for the calendar in force, so 29 February 1900 (which did not exist in the Gregorian calendar) is rejected while 29 February 2000 is accepted.