Doomsday calculator
Every Gregorian year has a weekday shared by a set of easy dates. Learn that weekday, count from the nearest anchor, and you can work out any date without opening a calendar.
2026 lands on Saturday
In doomsday numbering, the century anchor is 2 (Tuesday) and the year offset is 4. That lands on 6 (Saturday). 2026 is a common year, so January and February use the common-year anchors.
2026 highlighted calendar
Filled cells are memorable anchors. Soft cells are every other date that falls on Saturday.
Jan 2026
Feb 2026
Mar 2026
Apr 2026
May 2026
Jun 2026
Jul 2026
Aug 2026
Sep 2026
Oct 2026
Nov 2026
Dec 2026
Memorable doomsdays
Even months are the easy doubles: 4/4, 6/6, 8/8, 10/10, and 12/12. Odd months use “work 9 to 5 at the 7-Eleven”: 5/9, 9/5, 7/11, and 11/7. Add Pi Day, the last day of February, and Jan 3 for 2026.
Jan 3 · The 3rd in 3 years out of 4
Feb 28 · Last day of February
Mar 14 · Pi Day
Apr 4 · Even months double: 4/4
May 9 · Work 9 to 5
Jun 6 · Even months double: 6/6
Jul 11 · At the 7-Eleven
Aug 8 · Even months double: 8/8
Sep 5 · Work 9 to 5
Oct 10 · Even months double: 10/10
Nov 7 · At the 7-Eleven
Dec 12 · Even months double: 12/12
How to calculate it
Start with the year, find its doomsday weekday, then walk from one memorable date in the same month.
1. Find the anchor
First find the century weekday, then add the last-two-digits offset. The result is the year’s doomsday: the weekday shared by all the memorable dates.
2. Pick a nearby date
For December, use 12/12. For August, use 8/8. For September, use 9/5. These dates already sit on doomsday, so they are your stepping stones.
3. Count the gap
Move forward or backward from the nearby doomsday. Seven days changes the date but not the weekday, so only the leftover after whole weeks matters.
Weekday numbers
1 = Monday
2 = Tuesday
3 = Wednesday
4 = Thursday
5 = Friday
6 = Saturday
0 / 7 = Sunday
Try the year formula
2026 sits in the 2000s. That century starts on anchor 2 (Tuesday).
26 = 2 dozen years + 2 left over
offset = 2 + 2 + floor(2 / 4) = 4
(2 + 4) mod 7 = 6
So the doomsday for 2026 is Saturday. January uses Jan 3 because this is a common year.
Further reading: Doomsday rule on Wikipedia.