Tool to find the day of the week of a given date. Each date corresponds to a day of the week on a given calendar. There is an algorithm to calculate the day of the week of a date.

Day of the Week of a Date - dCode

Tag(s) : Date and Time, Fun/Miscellaneous

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The day of the week associated with a date is the name of one of the 7 days of the week: Monday, Tuesday, Wednesday, Thursday, Friday, Saturday or Sunday.

Weekday calculation for any given date (day, month, year) use the Gregorian Calendar (or Julian before 1582) and some mathematical formulas.

From a known current date (like today), calculate the number of days past or to come with the requested date to deduce the associated day of the week (calculation modulo 7).

__Example:__ Today is Monday, in 15 days it will be Tuesday (15 mod 7 = 1), Monday +1 = Tuesday.

There are algorithms that allow a mental calculation (not necessarily easy), but they become false for dates before 1900. Basically, the principle is to make a calculation from the numbers day, month, year, and deduce a modulo 7 value, with 0 for Monday, 1 for Tuesday, 2 for Wednesday, 3 for Thursday, 4 for Friday, 5 for Saturday and 6 for Sunday.

__Example:__ The first january 2000 was a Saturday.

Overall, it is highly probable that before 1900 the days of the week were not perfectly managed in all regions. The Gregorian calendar was not as widespread in Europe, and globally, the values proposed by dCode before 1900 are mathematically correct, but may have shifts with the practices of the time that were not rigorous.

To find the weekday, indicate the day, month and year of birth and dCode will calculate the corresponding day of the week.

There are two differences, the first difference is about the calculus of leap years and the second one, which is a consequence, the Gregorian Calendar had a jump of several days in 1582.

In France, the day after December 9, 1582, was December 20, 1582.

In Europe, the day after Thursday 4 October was Friday 15 October 1582 (this version is used on dCode).

When there may be confusion or uncertainty about the calendar used, historians specify the location and name of the calendar used.

__Example:__ January 1st of the Gregorian Calendar

dCode retains ownership of the "Day of the Week of a Date" source code. Except explicit open source licence (indicated Creative Commons / free), the "Day of the Week of a Date" algorithm, the applet or snippet (converter, solver, encryption / decryption, encoding / decoding, ciphering / deciphering, breaker, translator), or the "Day of the Week of a Date" functions (calculate, convert, solve, decrypt / encrypt, decipher / cipher, decode / encode, translate) written in any informatic language (Python, Java, PHP, C#, Javascript, Matlab, etc.) and all data download, script, or API access for "Day of the Week of a Date" are not public, same for offline use on PC, mobile, tablet, iPhone or Android app!

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Cite as source (bibliography):

*Day of the Week of a Date* on dCode.fr [online website], retrieved on 2023-09-30,

day,week,weekday,find,search,date,birthdate,year,calendar,monday,tuesday,wednesday,thursday,friday,saturday,sunday

https://www.dcode.fr/day-week-date

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