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Day of Week Calculator
Find the day of week for any date, view monthly calendars, or find all dates of a specific weekday.
💡 This calculator uses the Gregorian calendar.
📖 How to Use
- Date → Day: Select a date to find its day of the week
- View Calendar: Choose a year and month to see the calendar
- Find Dates by Day: Select year, month, and weekday to find all matching dates
✨ Features
- ✓Find day of week for any date
- ✓Monthly calendar display
- ✓Find all dates of a specific weekday
- ✓Weekend/weekday distinction
- ✓Supports years 1900-2100
📐 Formula
Zeller's formula: h = (q + ⌊13(m+1)/5⌋ + K + ⌊K/4⌋ + ⌊J/4⌋ + 5J) mod 7💡 How It Works
- •Day of week calculations are based on Gregorian calendar rules.
- •The Gregorian calendar was established by Pope Gregory XIII in 1582 and is now the global standard.
- •Leap years occur every 4 years, except for years divisible by 100, unless also divisible by 400.
- •Zeller's formula mathematically calculates the day of week for any date.
- •A week consists of 7 days from Sunday (0) to Saturday (6).
❓ FAQ
Q. What day was January 1, 2000?
A. January 1, 2000 was a Saturday.
Q. Can I find only Fridays in a specific month?
A. Yes, use 'Find Dates by Day' mode, select the year, month, and Friday to find all Fridays in that month.
Q. How are leap years calculated?
A. Divisible by 4 = leap year, but divisible by 100 = not a leap year, but divisible by 400 = leap year. Example: 2000 is a leap year, 1900 is not.
Q. Does this work for dates in the past?
A. Yes, this calculator supports dates from 1900 to 2100 using the Gregorian calendar.