Enter any date, and the tool calculates which day of the week it falls on using Zeller's congruence — works for any year.
It uses Zeller's congruence, a classic formula that computes the weekday directly from the day, month and year of a proleptic Gregorian date — no calendar lookup needed.
Yes, for dates in the Gregorian calendar. Note that many countries adopted the Gregorian calendar at different times before the 1900s.
Enter your date of birth and the tool tells you instantly which day of the week you were born.