The Seven-Day Week Through History
The seven-day week is one of the few human time units with no direct astronomical origin (unlike the day, month, or solar year). It has run unbroken across cultures and calendar reforms for millennia. Even when Pope Gregory XIII reformed the calendar in October 1582—dropping 10 days from the calendar (Thursday, October 4 was followed immediately by Friday, October 15)—the sequence of the weekdays was preserved without interruption.
Frequently Asked Questions
How do I find out what day of the week I was born?
Select your birth date in the calculator above. The tool instantly determines the exact weekday (Monday through Sunday) along with historical leap year details.
What is the Doomsday Algorithm?
Invented by mathematician John Conway in 1973, the Doomsday Rule is a mathematical formula that allows mental calculation of the day of the week for any given date in history using anchor dates that always share the same weekday.