How far back or forward does it work?

It works for any date the calendar can represent, covering well-known historical dates and dates far into the future, all on the proleptic Gregorian calendar used by modern software.

Does it account for leap years?

Yes. Leap years and the differing lengths of months are built into the calendar logic, so 29 February in a leap year and the days that follow it return the correct weekday.

Can I find the weekday I was born on?

Absolutely. Enter your date of birth and the calculator returns the exact day of the week you were born, from Sunday through Saturday.

Why might an old historical date seem off?

Many countries switched from the Julian to the Gregorian calendar at different times before 1923. This tool uses the Gregorian system throughout, so very old dates may differ from what local records of that era recorded.

Day of the Week Calculator

Date

Day of the WeekMonday

This day-of-the-week calculator tells you which weekday any date falls on, whether it is far in the past or the future. Give it a date and it returns the name of the day, from Sunday through Saturday. It is handy for finding the weekday you were born on, planning around a future date, or checking a historical anniversary against the Gregorian calendar.

Formula

dayName = WEEKDAYS[ weekdayIndex(date) ], indexed Sunday=0 … Saturday=6

date: The calendar date being looked up
weekdayIndex: The 0-6 weekday number the Gregorian calendar assigns to the date
WEEKDAYS: The ordered names Sunday through Saturday

How it works

Select the date you want to look up, including its year, month, and day.
The calculator reads the weekday index the calendar assigns to that date, where 0 is Sunday and 6 is Saturday.
It maps that index to the day name and displays it, correctly accounting for leap years and varying month lengths.

Worked example

What day of the week was 4 July 2024?

Enter the date 4 July 2024.
The calendar assigns this date weekday index 4.
Index 4 maps to Thursday.

4 July 2024 was a Thursday.

Frequently asked questions

How far back or forward does it work?: It works for any date the calendar can represent, covering well-known historical dates and dates far into the future, all on the proleptic Gregorian calendar used by modern software.
Does it account for leap years?: Yes. Leap years and the differing lengths of months are built into the calendar logic, so 29 February in a leap year and the days that follow it return the correct weekday.
Can I find the weekday I was born on?: Absolutely. Enter your date of birth and the calculator returns the exact day of the week you were born, from Sunday through Saturday.
Why might an old historical date seem off?: Many countries switched from the Julian to the Gregorian calendar at different times before 1923. This tool uses the Gregorian system throughout, so very old dates may differ from what local records of that era recorded.

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