Day of the Week Calculator — Free Online Calculator & Formula Guide
Find the day of the week for any date using Zeller's congruence. Features a perpetual calendar algorithm explanation and historical context.
Day of Week
Results below
Enter Values
Date
Monday, January 1, 2024
Month
1
Day
1
Year
2024
Zeller's Congruence
h = (q + ⌊13(m+1)/5⌋ + K + ⌊K/4⌋ + ⌊J/4⌋ − 2J) mod 7
Zeller Result (h)
2 → Monday
Formula Breakdown
q=1, m=13, K=23, J=20 → h = (1 + 36 + 23 + 5 + 5 − 40) mod 7 = 30 mod 7 = 2
First Day of Month
Monday
Days in Month
31
Scenario Comparison
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Day of the Week
Monday
Monday, January 1, 2024
h = (q + ⌊13(m+1)/5⌋ + K + ⌊K/4⌋ + ⌊J/4⌋ − 2J) mod 7
Step-by-step for this date:
q=1, m=13, K=23, J=20 → h = (1 + 36 + 23 + 5 + 5 − 40) mod 7 = 30 mod 7 = 2
1
q (day)
13
m (adj. month)
24
K (year mod 100)
20
J (century)
1
h (result)
Historical events for Monday, January 1, 2024 would appear here.
(Fun fact placeholder — connect to a history API for live data)
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