Julian to Gregorian Calendar
When the original change occurred there really were people who believed the Church had "stolen" 10 days from their lives… and they would now die 10 days earlier than originally intended. Also, Protestant and Eastern Orthodox controlled lands ignored the Roman Catholic decree.
Does this mean that official documents dated after the changeover refer to the Gregorian
Calendar? Not a chance. Some people added "OS" (Old Style) or "NS" (New Style) while others just wrote the day… using whichever calendar date that made sense to that person. Be very careful when using dates around a changeover year, and for some years after. It really is hard to get people to change old habits…
The Julian Calendar is currently 13 days behind the Gregorian Calendar (2003). Many Orthodox Churches still use the Julian Calendar as the standard for the church.
| Country/Region | Year | Days | Comments |
| Italy, Portugal, Spain | 1582 | 10 | 4 Oct 1582 Julian was followed by 15 Oct 1582Includes all Spanish colonies and possessions, such as Mexico |
| France | 1582 | 10 |
20 Dec followed 9 Dec. French possessions, such as Louisiana in North America, used the Gregorian Calendar from their founding. |
| Luxembourg | 1582 | 10 | 25 Dec followed 14 Dec |
| Zeeland, Brabant, and the Staten Generaal in modern-day Netherlands | 1582 | 10 | 25 Dec followed 14 Dec |
| Limburg and several other provinces | 1582/3 | 10 | 31 Dec followed 20 Dec. 1 Jan 1 followed 21 Dec in some cases Wonder what people thought of not having Christmas? |
| Holland | 1853 | 10 | 12 Jan followed 1 Jan |
| Switzerland | 1583-1812 | — | Parts of Switzerland made the change over many centuries, starting in 1583 and only being complete in 1812. |
| German Roman Catholic states, Belgium, and part of The Netherlands | 1584 | 10 | |
| Hungary | 1587 | 10 | |
| Prussia | 1610 | 10 | |
| Alcase | 1682 | 10 | |
| Protestant German states including Prussia | 1700 | 11 | Many of these states calculated Easter using the Tycho Brahe's method, but used the new calendar for civil and commercial affairs. They adopted the Gregorian rules for calculating Easter in 1776. |
| The Netherlands | 1700 | 11 | All of The Netherlands used the same calendar in this year. |
| Denmark, Norway | 1700 | 11 | |
| Sweden starts change | 1700 | Sweden phased in the change from 1700 to 1740 by exluding leap days. | |
| Sweden reverts back to Julian Calendar | 1712 | ||
| Tuscany | 1750 | 11 | |
| England, Scotland, Ireland, and Wales | 1752 | 11 | Wednesday, September 2, 1752 gave way to Thursday, September 14th. The first day of the year was also changed from March 25 to January 1. |
| English colonies including present-day USA, Australia, and Canada | 1752 | 11 | |
| Finland | 1753 | 11 | |
| Sweden | 1753 | 11 | Sweden finally made the switch in one change when 17 Feb was followed by 1Mar |
| Lorraine | 1760 | 11 | 28 Feb followed 16 Feb |
| Alaskan Territory | 1867 | 11 | This change to the new calendar occurred when the United States purchased Alaska from Russia. |
| Japan | 1873 | 11 | |
| Egypt | 1875 | 11 | |
| Thailand | 1889 | — | Kinda… |
| China | 1911 | Again in 1949… not sure when they reverted. | |
| Albania | 1912 | ||
| Latvia | 1915? | ||
| Lithuania | 1915 | ||
| Bulgaria | 1916 | ||
| Russia | 1918 | 12 |
14 Feb followed 31 Jan The Revolution of 1918 allowed reformers to adopt the calendar in use by most of their trading partners. The Russian Imperial Navy and academics dealing with westerners had been using the new calendar for many years (decades in some cases) but the internal civil calendar did not change until 1918. |
| Estonia | 1918 | 12 | |
| Romania | 1919 | ||
| Yugoslavia | 1919 | ||
| Greece | 1923 or 1924 | 12 | There is some disagreement about when Greece changed. |
| Iran | 1925 | 12 | |
| Turkey | 1927 | 12 |