Thursday, December 26, 2013

Julian vs Gregorian Calendar Dates

Compiled by Joy Ikelman, 2013. Disclaimers apply.

Julian vs Gregorian Calendar Dates

Nathan Boone, son of Daniel Boone, once said in an interview:

“I’ve shown you the family records, which, in my father’s own handwriting, show his birth to have been October 22, 1734. The date is according to the old calendar, or Old Style, as he and my mother always expressed their disapproval of adopting the New Style calendar.” [1]

What was Old Style? What is New Style? How do these effect genealogy?

The Julian Calendar
The “Old Style” calendar was the Julian calendar, which had been introduced by Julius Caesar in about 45 BC. This was the first, standardized, calendar used around the world to organize societies, religious celebrations, and commerce. It had 365 days in it, more or less, but needed to be adjusted occasionally. Not every country used it this calendar; many cultures had their own. [2] However, the Julian calendar was used in most of Europe, and in European settlements in the Americas through the mid-1700s.

The Gregorian Calendar
In 1582, the calendar was “reformed” under Pope Gregory VIII’s edict. This was the Gregorian calendar. It was what people called the “New Style.” The goal was to create a more logical placement of Easter. [3] In the Julian calendar, Easter was tied to the Spring Equinox. This “pagan” association, along with others, was against Catholic doctrine. Another example that caused concern was Winter Solstice and Saturnalia combined with Christmas.

The calendar reformers mathematically corrected several other vexing errors of the Julian calendar, such as extra days and inconsistencies. The Gregorian calendar was adopted in 1582 by most Catholic countries of Europe. [4] It took five Centuries for all countries to adopt the new calendar, at least for commerce and trade purposes. In September 1752, Britain and the British Empire (which included the eastern part of the United States) officially adopted the Gregorian calendar as a result of the British Calendar Act of 1751. [5]

The Calendars and Genealogical Records
My research on the Wests in New England has led me to the early records of the Massachusetts Bay Colony. The records from the 1600s in Essex County, Massachusetts (including Salem, Beverly, Lynn, Ipswich, Bradford, etc.) are often oddly dated. [6] As an example, Valentine’s Day could be recorded in court documents as:

14 Feb 1663-1664
14 Feb 1663, 1664
Febr 14, 63,64 (no space between years)
14 da 12 mo 1663 (this style is often used in Quaker records)
14: 12: 63 (found in early Salem records before 1640)

Where did that “12” come from? Isn’t December the twelfth month of the year?

In the (Old Style) Julian calendar, February was the last (twelfth) month of the year. March was the first month of the new year. The etymological origins of September, October, November, and December were seven, eight, nine, and ten. We still retain the month names but now these are the last four months of the year. New England would not officially adopt the (New Style) Gregorian calendar for nearly one hundred years.

Court Records and Church Records
In court record transcriptions in New England (1600s), the double-dating most often occurs in the months of January, February, and March. Church records of the time generally avoided double-dating. The reasoning for this was partly political. Many churches refused to give any authority to the Catholic Church. Therefore, they continued to use the Old Style of dating until they absolutely had to change, which was in September of 1752.

How to Place Dates into Your Research
The best advice is to copy the dates EXACTLY as you see them in the source material. That is, copy the abbreviations, commas, colons, and whatever else you see. [6] Explain to the reader a bit about the Old Style/New Style calendars if this needed. If you must rework a date from Julian to Gregorian for any reason, do it the correct way, and then inform the reader what you have done. Go to Cyndi’s List (free service) for conversion calculators. [7]

What do you do if you are entering a year into a genealogy software program? You will want to use the earlier of the two year-dates. For example, if the source material says “1663, 1664” use “1663.” Most programs now have an area for notes. This is where you could explain the calendar difference.

Conclusion: George Washington
Here is an example you might recognize. George Washington was born (under the Julian calendar) on 11 February 1731. Under the Gregorian calendar, the date is 22 February 1732. Congress moved his birthday to the “New Style” calendar. [8] This is why we celebrate Washington’s birthday on February 22, instead of his original birth date of 11 February.

1. “My Father, Daniel Boone. The Draper Interviews with Nathan Boone.” Neil O. Hammon ed; The University Press of Kentucky, 1999.
2. Information derived from
3. Information derived from
4. Ibid.
5. The text of the British Calendar Act of 1751 is found at:
6. Records and Files of the Quarterly Courts of Essex County, Massachusetts. Volume I through 9; 1636-1686. These are court records of the Massachusetts Colony. Preserved by the Essex Institute in Salem.
6. Genealogy in Time Magazine suggests that you do not use a “slash” such as 14 Feb 1663/64. You should, when possible, write this out as 1663, 1664.
7. Cyndi’s List calculators are at

8. National Archives Web site:

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