Calendar proposal has fixed dates

Dick Henry, Johns Hopkins University proposed the Calender and Time Plan

Sometimes all it takes is a frustrated professor named Dick Henry, annoyed with the task of recreating the schedule every year, to create a more efficient calendar system in which every date falls on the same day of the week every year:

The current calendar, which runs for 365 days, was instituted by Pope Gregory in 1582 to bring the length of the year in line with the seasons. But because the Earth actually orbits the Sun every 365.24 days, a 366-day “leap year” must be added every four years to account for the extra fraction of a day. In this Gregorian system, a given date (such as New Year’s Day) falls on different days of the week in different years because 365 is not evenly divisible by seven.

That means new calendars must be printed every year, and the dates for recurring events constantly recalculated. So Henry designed a calendar that uses 364 days, which breaks down evenly into 52 weeks. In his so called “Calendar-and-Time” (C&T) plan, each month contains 30 or 31 days. He decided on each month’s length by forbidding the new calendar to differ from the old one by more than five days and by setting Christmas Day, 25 December, to always fall on a Sunday.

His constraints meant eight months would have different lengths than they do now. March, June, September, and December would each contain 31 days, while the other months would each get 30. To keep the calendar in synchronisation with the seasons, Henry inserted an extra week – which is not part of any month – every five or six years. He named the addition “Newton Week” in honour of his favourite physicist, Isaac Newton.

related links

Calender Reform Proposal
Professor Dick Henry’s Personal Page
The C & T calender
New Scientist: Novel calendar system creates regular dates
(via Boing Boing: Rational calendar with 364 days, extra week celebrating Isaac Newton)


  1. This was done by Isaac Asimov some years ago if I remember correctly. I think his suggestion was to work it out so that every now and again there was a Leap Day to correct errors and that day would be a World Holiday…

  2. It does make scence to make the calender more ‘metric’ as it were… wonder whats stopped this from actually being implimented by some one

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