Day of the week calculator Free
Find the weekday of any date from year 1 to 9999, plus its day of the year, ISO week number, leap year status and days from today.
Dates before 15 October 1582 are calculated on the proleptic Gregorian calendar. All calculations are whole-number calendar arithmetic, so time zones cannot shift the result.
About Day of the week calculator
Enter a date and the calculator tells you which day of the week it falls on, along with its day number in the year, its ISO 8601 week number, whether the year is a leap year, how many days are left in the year and how far it is from today.
It covers every year from 1 to 9999 using whole-number calendar arithmetic, so the answer never shifts by a day because of your time zone or daylight saving time. Dates before 15 October 1582 are calculated on the proleptic Gregorian calendar, which extends today’s calendar backwards.
How to use it
- Pick a date with the date picker, or type the year, month and day separately (the separate fields accept any year from 1 to 9999).
- Read the weekday and the other facts below; they update as you type.
- Press Today to jump back to the current date on your device.
Good to know
- Before 1582 most of Europe used the Julian calendar, so historical documents from that time can name a different weekday than the proleptic Gregorian date shown here.
- Days from today use the date on your device’s clock.
- Week numbers follow ISO 8601 (weeks start on Monday, week 1 contains the first Thursday). Some countries and calendars number weeks differently.
Questions and answers
Why does 1 January sometimes belong to week 52 or 53?
In the ISO system a week belongs to the year that contains its Thursday. If 1 January falls on a Friday, Saturday or Sunday, that week is the last week of the previous year.
Is 1900 a leap year?
No. Years divisible by 100 are leap years only if they are also divisible by 400, so 1900 and 2100 are not leap years and 2000 was.
What is the proleptic Gregorian calendar?
It is the Gregorian calendar extended to dates before it was introduced on 15 October 1582. It is the standard used by ISO 8601 and most software, but it does not match the Julian dates written in older records.