Understanding the Medieval Calendar


Medieval German Calendar

Each year, in December, I purchase a locally produced calendar that I hang on the back of my pantry door. Not only does it become an attractive addition to the kitchen but it is an invaluable tool on which I scribble birthday reminders, medical appointments, dinners and special events. In fact I would be completely lost without it.

The modern (or Gregorian) calendar is the most widely accepted calendar in the world with the day, month and year easy to understand. But this was not always the case. Its predecessor, the Julian Calendar, introduced by Julius Caesar in 45 BC was based on a common (or accepted year) that consisted of exactly 365 days, divided into 12 months with a leap day added in February. But, unfortunately, this led to a year consisting of 365.25 days, with the extra .25 day causing several problems. An inaccuracy with calculations concerning the introduction of the leap year (it was added every three years instead of four) had lasting ramifications. With so many extra days, the date for Easter (the most important event on the Christian calendar) was pushed out of alignment with cycle of the moon.


Pope Gregory XIII chairs the commission for reforming the Julian calendar in 1582.

The Gregorian calendar (named for Pope Gregory XIII) is solar based and uses the 365 day principal, but divides the months into 12 irregular lengths –  28, 30 or 31 days, with the strict observance of the leap day added at the end of February in each fourth year.

The difference between the two calendars may appear confusing, but to simplify, the Julian calendar allowed an error of 1 extra day in every 128 years.

The Georgian Calendar was not introduced in Great Britain until September 1752 and in order to synchronise with other countries (including Spain, Italy and Portugal) the ‘extra’ 11 days that had slowly pushed the Julian calendar forward, had to be lost or dropped. When researching events in the medieval period (particularly birth, death and marriage dates) it is worthwhile to keep these adjustments in mind.

Medieval society measured their years, not via the consecutive numbering system as we do today, but by a system known as Regnal years, calculated from the official date of the reigning monarch’s accession to the throne. For example King Edward III commenced his reign on 25th January 1327 and any official correspondence after this date would have included the number of years he had reigned. For example, the following date appears at the bottom of a letter written by Catherine to her sister Cecile in The Lily and the Lion (Chapter 4, page 44).

Written from the King’s Arms, village of Aylesbury, Feast of Pope Saint Julius,

12 April 34 Edward III

 The date has been written as 12 April 34 Edward III (the 34th year in the reign of Edward III) so can be understood to be the 12th of April 1361 (1327 + 34 = 1361).

When a monarch dies, abdicates or is deposed the regnal year comes to an end and the new date begins with the next monarch.  Edward III died 21st June 1377 and correspondence despatched on the following day would have been dated 22nd June 1 Richard II

A full list of the regnal years (and several exceptions to the above) can be found on Wikipedia http://en.wikipedia.org/wiki/Regnal_years_of_English_monarchs.


Dionysius Exiguus

Anno Domini (Latin for ‘In the Year of Our Lord’), shortened as AD or A.D refers to the years after the birth of Jesus and was invented by Dionysius Exiguus in about AD 525. He fixed the point at which the both the Gregorian and Julian calendars record the passing of the years. During the 15th and 16th centuries, the Anno Domini date system became popular with the general populace and slowly overtook the use of the regnal system.

With my hectic lifestyle and obsession with writing, I thank the heavens for my easy to read, cheap kitchen calendar given that this week alone I was able to completely confuse Tuesday with Thursday!

Cathy A


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