The Change from the Julian to the Gregorian Calendar

The Gregorian calendar, which is the calendar used today, was first introduced by Pope Gregory XIII via a papal bull in February 1582 to correct an error in the old Julian calendar.

This error had been accumulating over hundreds of years so that every 128 years the calendar was out of sync with the equinoxes and solstices by one additional day.

As the centuries passed, the Julian Calendar became more inaccurate. Because the calendar was incorrectly determining the date of Easter, Pope Gregory XIII reformed the calendar to match the solar year so that Easter would once again "fall upon the first Sunday after the first full moon on or after the Vernal Equinox.".

Ten days were omitted from the calendar to bring the calendar back in line with the solstices, and Pope Gregory XIII decreed that the day following Thursday, October 4, 1582 would be Friday, October 15, 1582 and from then on the reformed Gregorian calendar would be used.

The Catholic countries of Italy, Poland, Portugal, and Spain immediately observed the calendar change, but for almost two hundred years Protestant countries refused to change to the new calendar because it had reformed by a Catholic Pope. The Greek Orthodox countries didn't make the change until the start of the 20th century.

The following list contains the dates for changes from the Julian to the Gregorian calendar. However, the since the map has changed considerably in the four hundred years since the first calendar update, be aware of possible boundary changes that may have occurred.

Country End Julian Calendar Begin Gregorian Calendar
Albania Dec 1912 Dec 1912
Austria
    Tyrol
    Carinthia, Styria

Oct 5, 1583
Dec 14, 1583

Oct 16,1583
Dec 25, 1583
Belgium
    Spanish Provinces
    Liege

Dec 21, 1582
Feb 10,1583

Jan 1, 1583
Feb 21,1583
Bulgaria Nov 1, 1915 Nov 14, 1915
China Dec 18, 1911 Jan 1, 1912
Canada
    British Colonies
    Nova Scotia

Sep 2, 1752
Sep 2, 1752

Sep 14, 1752
Sep 14, 1752
Czech Republic - Bohemia / Moravia Jan 6, 1584 Jan 17, 1584
Denmark
    Faero Islands
Feb 18, 1700
Nov 16, 1700
March 1,1700
Nov 28, 1700
Egypt 1875 1875
Estonia Feb 1, 1918 Feb 15, 1918
Finland (part of Sweden) Feb 17, 1753 March 1, 1753
France & Colonies
    Alsace
    Strasbourg
Dec 9, 1582
1648
Feb 5, 1682
Dec 20, 1582
1648
Feb 16,1682
Germany, Catholic Regions
    Augsburg
    Baden
    Bavaria
    Cologne
    Julich
    Mainz
    Munster, Strasbourg
    Trier
    Wurzburg

Feb 13, 1583
Nov 16, 1583
Oct 5, 1583
Nov 3, 1583
Nov 2, 1583
Nov 11, 1583
Nov 16, 1583
Oct 4, 1583
Nov 4, 1583

Feb 24, 1583
Nov 27, 1583
Nov 16, 1583
Nov 14, 1583
Nov 13, 1583
Nov 22, 1583
Nov 27, 1583
Oct, 15, 1583
Nov 15, 1583
Germany, Protestant Regions
    Hildesheim
    Kurland
    Minden
    Neuburg
    Osnabruck
    Paderborn
    Prussia
    Westphalia
    All Others

Mar 15, 1631
1617
Feb 1, 1668
Dec 13, 1615
1624
June 16, 1585
Aug 22, 1610
July 1, 1584
Feb 18, 1700

March 26, 1631
1617
Feb 12, 1668
Dec 24, 1615
1624
July 27, 1585
Sept 2, 1610
July 12, 1584
March 1, 1700
Great Britain & colonies Sept 2, 1752 Sept 14, 1752
Greece Sept 14, 1916 Sept 28, 1916
Holy Roman Empire Jan 6, 1584 Jan 17, 1584
Hungary
    Transylvania
Oct 21, 1587
Dec 14, 1590
Nov 1, 1587
Dec 25, 1590
Iceland Nov 16, 1700 Nov 28, 1700
Ireland Sept 2, 1752 Sept 14, 1752
Italy Oct 4,1582 Oct 15, 1582
Japan 1873 1873
Latvia Feb 1, 1918 Feb 15, 1918
Lithuania Feb 1, 1918 Feb 15, 1918
Moravia (Czech Republic) Jan 6, 1584 Jan 17, 1584
The Netherlands
    Holland, North Brabant
    Gelderland, Zutphen
    Utrecht, Overijssel
    Friesland, Groningen
    Drente

Dec 21, 1582
June 30, 1700
Nov 30, 1700
Dec 31, 1700
April 30, 1701

Jan 1, 1583
July 7, 1700
Dec 12, 1700
Jan 12, 1701
May 12, 1701
Norway Feb 18, 1700 March 1, 1700
Poland
    Silesia
Oct 4, 1582
Jan 12, 1584
Oct 15, 1582
Jan 23, 1584
Portugal Oct 4, 1582 Oct 15, 1582
Romania
   Transylvania
March 31, 1919
Dec 14, 1590
April 14, 1919
Dec 25, 1590
Russia Jan 31,1918 Feb 14, 1918
Spain
    American Colonies
Oct 4, 1582
1584
Oct 15, 1582
1584
Sweden Feb 17, 1753 March 1, 1753
Switzerland
    Catholic Cantons - Lucern, Uri,     Schwyz, Zug, Freiburg, Solothurn
    Wallis
    Protestant - Zurich, Bern, Basel,     Schaffhouse, Geneva, Thurgovia
    Appenzell, Glarus, St. Gallen

Jan 11, 1584
Jan 11, 1584
Feb 28, 1655
Dec 31, 1700
Dec 31, 1700
1724

Jan 22, 1584
Jan 22, 1584
March 11, 1655
Jan 12, 1701
Jan 12, 1701
1724
Turkey 1927 1927
United States
    British Colonies
    Spanish Colonies
    Alaska

Sept 2, 1752
1584
Oct 5, 1867

Sept 14, 1752
1584
Oct 18, 1867
Yugoslavia March 4, 1919 March 18, 1919

Nova Scotia

Nova Scotia, while under French Catholic control, used the Gregorian calendar from 1605 until Oct. 13, 1710 when it reverted to the Julian calendar, when the British took over. It changed to the Gregorian calendar with other British colonies on Sep 14, 1752.

Sweden

Sweden decided to make a more gradual change from the Julian to the Gregorian calendar. Instead of taking 11 days out of the calendar in one year, it planned to drop a day every leap year from 1700 through 1740 until the eleven extra days were omitted. By 1740 it would be in line with the new Gregorian calendar and other countries.

By 1712, when Sweden's calendar no longer corresponded with either the Julian and the Gregorian calendar, the country reverted back to the Julian calendar. To do this, they inserted an extra day in the leap year 1712, making that year a double leap year. Thus in 1712, February had 30 days in Sweden. In 1753, Sweden changed to the Gregorian calendar by dropping 11 days.

Finland was a part of Sweden until 1809, when Russia, who was still using the Julian calendar, took over Finland. Although there was some use of the Julian calendar, the Gregorian calendar remained official in Finland.



Notation

In many countries the Julian Calendar was used by the general population long after the official introduction of the Gregorian Calendar. Events were recorded in the 16th to 18th Centuries with various dates, depending on which calendar was used. Dates recorded in the Julian Calendar were marked "O.S." for "Old Style", and those in the Gregorian Calendar were marked "N.S." for "New Style".



Double Dating

New Year's Day had been celebrated on March 25 under the Julian calendar in Great Britain and its colonies, but with the introduction of the Gregorian Calendar in 1752, New Year's Day was now observed on January 1. When New Year's Day was celebrated on March 25th, March 24 of one year was followed by March 25 of the following year. When the Gregorian calendar reform changed New Year's Day from March 25 to January 1, the year of George Washington's birth, because it took place in February, changed from 1731 to 1732. In the Julian Calendar his birthdate is Feb 11, 1731 and in the Gregorian Calendar it is Feb 22, 1732. Double dating was used in Great Britain and its colonies including America to clarify dates occurring between 1 January and 24 March on the years between 1582, the date of the original introduction of the Gregorian calendar, and 1752, when Great Britain adopted the calendar.

Double dates were identified with a slash mark (/) representing the Old and New Style calendars, e. g., 1731/1732.


© Copyright 1997 - 2015 -- All Rights Reserved. This article may not be published, broadcast, rewritten, or redistributed without prior written permission from the author.

Source of some data: Book of Calendars, The; Parise, Frank, editor: Mapping Time, Richards, E.G. Licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License

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