Day of Week Calculator
Find the weekday of any date, plus its day of year and Julian day number.
Last updated: August 2026
Use YYYY-MM-DD.
Day of week
Monday
Day of year
222
Julian day
24,61,263
Leap year
No
2026 has 365 days
How it works
Weekday from the Gregorian calendar; day of year = days since Jan 1; Julian day = continuous day count since 4713 BC.
Example: 10 Aug 2026 is a Monday (day of year 222).
Frequently Asked Questions
How do I find what day of the week a date was?
Enter the date and the calculator returns the weekday directly. For example, 15 August 2026 was a Saturday.
What is a Julian day number?
It is a continuous count of days since 1 January 4713 BC, used in astronomy and computing to compare dates without calendars.
What is the day of year?
It is the position of the date within the year — January 1 is day 1 and December 31 is day 365 (or 366 in a leap year).
Do dates and weekdays repeat in a fixed cycle?
Yes. The full cycle of dates and weekdays repeats every 28 years on the Gregorian calendar, which is why old calendars can be reused after 28 years.