Determine the exact day of the week (Monday through Sunday) for any historical or future calendar date using Zeller's Congruence algorithm.
The Day of the Week Calculator identifies the exact weekday for any calendar date across human history or the distant future. Whether you want to know what day of the week you were born on, find out what weekday July 4, 1776 fell on, or determine whether Christmas in 2030 falls on a weekend, this tool provides instant mathematical certainty.
Powered by Zeller's Congruence algorithm and Doomsday Rule principles, the calculator provides calendar trivia, the number of days until or since the date, and historical context.
Genealogists verify family bible records and census entries by matching recorded dates against historical days of the week.
Parents discover the weekday of their child's birth to print on birth announcement cards and nursery art.
Couples select future anniversary dates that fall conveniently on a Saturday or Sunday.
Select the month, day, and year using the date picker or input fields.
The tool determines the day of the week instantaneously.
Explore the full weekday name, days elapsed or remaining, and calendar facts.
Instant calculation based on Zeller's Congruence mathematical algorithm
Supports historical dates from Year 1 to distant future dates
Calculates total days elapsed since the date or days remaining until future dates
Identifies the exact day of the year (Day 1 to Day 366) and ISO week number
100% private in-browser computation with zero tracking
Find what day of the week Neil Armstrong walked on the moon.
Instant mathematical verification using Zeller's Congruence.
Solution: Britain and its American colonies used the Julian calendar until September 1752, when 11 days were skipped to align with the Gregorian calendar.
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Zeller's Congruence is an algorithm devised by Christian Zeller in 1882 to calculate the day of the week for any Gregorian or Julian calendar date using modular arithmetic.