Day of Week Calculator
Gregorian and Julian Calendars
Day of Week
Do not enter a date between Oct 5, 1582 and Oct 14, 1582. These dates did not exist in the conversion.
The math behind this is explained in source code comments.
Leap Year Facts
Midpoint between two dates/times
Also, add or subtract to/from a date/time.
Programming day-of-week from date
Determine dates in your head
. If you know today's date, you are all set.