Julian and Gregorian Calendars
The official calendar used in most of the modern world today is the Gregorian, named after Pope Gregory. It is based on the earth’s movement in relation to the sun with common and leap years comprising 365 and 366 days respectively.
When the old Julian calendar (which added 11 minutes every year) was replaced by the more accurate Gregorian calendar in 1582, only a few countries accepted the change. It took almost 400 years before all of Europe adopted the new standard.
Dates recorded from 1582 to 1919 that crossed the two systems can be confusing to family history researchers. For 46 years Benjamin Franklin’s birth day was January 6, 1706. He was “reborn” to January 17th when the British Colonies adopted the Gregorian Calendar in 1752.
A chart which shows when countries changed from Julian to Gregorian and a converter that translates dates from a variety of calendars are among the tools available to navigate through this maze. Interesting historical reading about how a monarch's reign influenced the English calendar is found in the article Regnal Years in England.
|Country|| Start numbered year
on 1 January
| Adoption of|
|Denmark|| Gradual change from
13th to 16th centuries
|Holy Roman Empire||1544||from 1583|
|Dutch Republic||1583||from 1582|
| Britain and
- Herluf Nielsen: Kronologi (2nd ed., Dansk Historisk Fællesforening, Copenhagen 1967), pp.48-50.
- Le calendrier grégorien en France
- Per decree of 16 June 1575. Hermann Grotefend, "Osteranfang" (Easter beginning), Zeitrechnung de Deutschen Mittelalters und der Neuzeit (Chronology of the German Middle Ages and modern times) (1891-1898)
- Blackburn & Holford-Strevens (1999), p. 784.
- John J. Bond, Handy-book of rules and tables for verifying dates with the Christian era Scottish decree on pp. xvii–xviii.
- Roscoe Lamont, The reform of the Julian calendar, Popular Astronomy 28 (1920) 18–32. Decree of Peter the Great is on pp.23–24.