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. Before 1752 the 1st day of the new year was 25 of March, and in places, such as New England you will find dates recorded with a slash such as February 14, 1701/02. 1702 would not have actually begun until after March 25. Using the double dating and understand its purpose can be helpful in recording family historical events.

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.