Date & Time
Day of Week Calculator
Find what day any date falls on.
Find the day of week for any date.
Zeller's Formula
Mathematical algorithm from year, month, day.
Doomsday Algorithm
Conway's mental method using anchor days.
Why It Matters
- Historical research
- Legal documents
- Scheduling
Frequently Asked Questions
July 4, 1776?
Thursday.
Mental calculation?
Doomsday algorithm with century anchors.
Calendar repeats?
Every 400 years exactly.