What is the Doomsday for the year...
2026
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The Doomsday Rule
Created by mathematician John Conway, the Doomsday Rule lets you calculate the day of the week for any date in your head. It relies on the fact that certain dates (Doomsdays) always share the exact same day of the week in a given year.
Step 1
Century Anchors
Every century has an anchor day. The pattern repeats every 400 years:
- 1800s: Friday (5)
- 1900s: Wednesday (3)
- 2000s: Tuesday (2) Current Century
- 2100s: Sunday (0)
Memory Trick: "We-Take-Sunday-Flight" (Wednesday, Tuesday, Sunday, Friday) starting at 1900.
Step 2
Find the Year's Doomsday
Let y be the last two digits of the year (e.g. 26 for 2026):
- Divide y by 12: quotient a, remainder b.
- Divide the remainder b by 4: quotient c.
- Add a + b + c plus the Century Anchor day.
- Modulo 7 is the year's Doomsday.
Doomsday = (Anchor + a + b + c) mod 7
Step 3
Doomsday Dates (Month Anchors)
These dates are ALWAYS the year's Doomsday. Memorize them with these simple rules:
Jan
3 / 4*
3rd (common), 4th (leap)*
Feb
28 / 29*
Last day of Feb
Mar
14
Pi Day (3/14)
Apr
4
Even month (4/4)
May
9
"9 to 5" (9th of May)
Jun
6
Even month (6/6)
Jul
11
"7-Eleven" (11th of July)
Aug
8
Even month (8/8)
Sep
5
"9 to 5" (5th of Sept)
Oct
10
Even month (10/10)
Nov
7
"7-Eleven" (7th of Nov)
Dec
12
Even month (12/12)
Odd Month Trick: "Working 9-to-5 at the 7-Eleven". May 9 (9/5) & Sep 5 (5/9) pair up. Jul 11 (11/7) & Nov 7 (7/11) pair up.
Step 4
Find the Target Date's Day
Compare your target date to that month's Doomsday anchor. Calculate the difference, mod 7, and count forward or backward from the year's Doomsday.
Example: What day is 15th June 2026?
- 2026 Doomsday is Saturday (from Step 2).
- June's anchor is June 6th (6/6).
- June 15th is 9 days after June 6th (15 - 6 = 9).
- 9 mod 7 = +2 days.
- Saturday + 2 days = Monday. June 15th, 2026 is a Monday!
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