Gregorian Calendar Adjustment

Our modern civic calendar is also known as the “Gregorian” calender, from an adjustment mandated by Pope Gregory XIII to the “Julian” calendar that had been used in Europe and elsewhere for one and a half millennia. Adoption of the Gregorian adjustment meant two things.

The first was a change in the calculation of leap years, which only had the minor affect of the presence or lack of 29 Feb in century years. Every century year (1600, 1700, 1800, etc.) was a leap year in the Julian calendar, but in the Gregorian only those that were divisible by 400 were leap years.

The far more significant change was the removal of a block of days to align the calendar with the seasons, and unfortunately this varies by location. On the day following this change, the location was using the Gregorian calendar, and the next year was a full Gregorian calendar year.

Fortunately, the missing dates generally won't cause any problems; the days will simply never show up in any official documents. However, they could cause confusion if one tries to compare dates between locations or to calculate the number of days between two dates when those dates are using different calendars.

In most (but not all) cases, the day of the week was unaltered at the calendar change. Thus a Tuesday date in the Julian calendar was followed by a Wednesday date in the Gregorian. Exceptions are noted in the table below.

Also note that, in the year following the adoption of the Gregorian calendar the first day of the numbered year was generally 1 January. This change has a significant impact on genalogists. For more on the first day of each year, see Beginning of the Year.

Locations Not Using the Julian Calendar

For locations that weren't using the Julian calendar before adopting the Gregorian, there is no simple day adjustment, and the entire calendar was simply replaced. This may have been done only at an official level to ease relations with other areas, leaving the traditional calendars intact for the population, or it may have been an abrupt change for both.

These non-Julian calendars are described in a simple way on this page, but are not fully discussed. You might want to try Cyndi's List - Calendars & Dates for a selection of resources on your particular needs. Or use your favorite search engine and look for the keywords gregorian, date, and conversion. You might also add the name of the country or location about which you are concerned to the list of keywords.

Civil and Church Adoption

All of these adoptions are for the “civil” governments. In most cases, the churches followed suit, but there are exceptions. I can't guarantee that I have found and described all of these, though I have tried to do that.

For instance, it is wise to be wary of dates recorded in documents created by members of many of the churches of Eastern Europe. These bodies did not accept the civil adjustments and continued to use their own calendars.

Using the Table

The table below lists the changes for current, sovereign states. Locations that might have been independent or part of a different country at the time of change, and which have a different date of changeover, are noted. Some regions may be be shown under multiple sovereign states.

For each state or region, the table shows the year of adoption of the Gregorian adjustment, and the dates that were lost to accomplish the adjustment. For example, if the column shows “5 Oct–14 Oct” then 4 October was followed the next day by 15 October.

In all cases below, the main location (i.e., the sovereign nation) is given in English, and alphabetized by the country name, not including qualifiers such as “Republic of.” However, within those countries, I've tried to use the official “local” name for locations in general. Local names that don't use the Latin alphabet have been translated.

This table only shows the conversions to the Gregorian calendar. Some countries may have had other calendar conversions within the range of years that is generally important to genealogists, but those aren't covered here.

References to the Common Era (c.e.) refer to the international standard year, also known as a.d.

If you have verifiable corrections or additions to any of this, please let us know.

Caveat: It is difficult to refer to city-state or country boundaries as these are subject to a great deal of change. And, of course, people are people. Some may not have heard about the change, others may initially reject it for their own reasons. Others may not care, and mistakes can be made. (How many times have you written the wrong year in early January?) Please take any statements here as approximations to help with your own researches.

Note: This table is incomplete and may be augmented over time. It currently lists most of the countries of Europe and North America (where our own genealogies are currently situated) and a few other countries. Items marked by tbd are specific points that need to be resolved.

Gregorian Calendar Adoption by Location
LocationYearLost Dates
Prior to 1912, Albania was part of the Ottoman Empire and used the Islamic calendar. The Gregorian calendar was adopted Dec 1912.
Andorra1582(see text)
In 1582, Andorra was co-ruled by the French monarchy and the bishop of La Seu d'Urgell (Catalonia, Spain). I haven't found a specific reference, but I suspect they changed calendars with the civic government of France, losing 10–19 Dec. The other possibility is that they converted two months earlier with Spain, which implemented the papal decree immediately, losing 5–14 Oct.
Austria15847–16 Jan
Brixen, Salzburg, Tirol15836–15 Oct
Kärnten, Steiermark158315–24 Dec
Australia was not colonized by Europeans until the establishment of a settlement at Port Jackson, in what would become New South Wales, on 26 January 1788. Prior to this, and continuing afterward for the various aboriginal groups who remained independent, the dating would have been by the traditions of those groups.
Bosnia and Herzegovina1878(n/a)
Prior to 1878, Bosnia (including what is now Herzegovina) was part of the Ottoman Empire, and used the Islamic calendar. However, as of the Treaty of Berlin of 1878, the territory, while formally remaining a part of the Ottoman Empire, was ceded to the occupation and administration of the Austro-Hungarian Empire, and would have officially used the Gregorian calendar.
Prior to the establishment of European colonies in what is now Canada, the various tribal nations that occupied the land had their own traditions for tracking time. These traditions would have continued after European settlement for the various tribal nations who remained independent.
English Colonies17523–13 Sep
The English (and for a short period, one Scottish) territories at the time were along the North Atlantic coast, including present areas of Newfoundland, Nova Scotia, Prince Edward Island, New Brunswick, and much of the central portion of Canada, centered on Hudson Bay. They probably also had a presence along the Pacific Coast.
French Colonies158210–19 Dec
The French territories were largely in the St. Lawrence River Valley. The area was ceded to England in 1763 following the “Seven Years War” and become Quebéc. This included the lightly-populated English-speaking area of Ontario. From 1783 to 1796, United Kingdom loyalists who left the new United States were each granted 200 acres in Ontario, which formally separated from Quebéc in 1791.
China, People's Republic of (aka Mainland China)1949(n/a)
Mainland China was part of the Republic of China (ROC) at the founding of ROC. (See "China, Republic of" below.) However, in 1949 the People's Republic of China (PRC) took control over the mainland. This government continued the Gregorian calendar but abolished the ROC standard of naming years since 1912, and only allowed the international convention.
China, Republic of (aka Taiwan)1912, 1929(n/a)
On its founding in 1912, the Republic of China (ROC) adopted the general principles of the Gregorian calendar. Prior to this time, the tradition was to use the imperial system based on the reign of the emperor. However, internal struggles (continuations of the instability that led to the founding of the ROC) fragmented mainland China into a number of areas controlled by individual warlords using their own calendars. By 1928, Chiang Kai-shek re-established control of the ROC over the mainland, and restored the Gregorian calendar as of 1 Jan 1929.

With the adoption of the Gregorian calendar, the Western year 1912 became the year 1 in the ROC calendar. The numbering of years may also use the international convention for year numbering. For example, 16 Jun 2006 could be written as 2006-06-16, or as R.O.C. 94-06-16. (If a two-digit year is found, it may indicate the ROC year numbering system, but care should probably be taken.)
Croatia19231–13 Oct
Czech Republic1584tbd
Denmark170019–28 Feb
Færø Islands170017–27 Nov
The Gregorian calendar is used for secular and business purposes. Prior to its adoption, dates were most commonly based on the Islamic or Coptic calendars. Even after the adoption, these alternate calendars still have official status. The Islamic calendar is used to fix religious observances, and the Coptic calender (based on the ancient Egyption calendar, which is also the basis for the Julian and Gregorian calendars) is used by the Coptic Orthodox Church, and in a modified form by many farmers.
England (see United Kingdom)
Estonia19181–13 Feb
Finland1700–1753(see note)
Finland was a territory of Sweden when the calendar changed. See the entry for Sweden for more information.
France1582, 180510–19 Dec
France originally changed to the Gregorian calendar in 1582. However, the French Revolution spurred the use of what is known as the “French Republican Calendar” or the “French Revolutionary Calendar.”

This calendar took effect on 24 October 1793, and referenced the first year as beginning on 22 Sep 1792 (the day the French Republic was proclaimed, known as 1 Vend�miaire an I in the new calendar). On 1 Jan 1806 (the day after 10 Niv�se an XIV in the Republican calendar), the Gregorian calendar was reinstated by Napoleon Bonaparte. It apparently made a very brief return in Paris after an uprising within the city, from 18 or 26 March to 28 May 1871.
Duchy of Lorraine1582–173510–19 Dec
Strasbourg16826–15 Feb
tbd The following information is in need of considerable reasearch.
Augsburg158314–23 Feb
Baden, Strasbourg158317–26 Nov
Bayern, Freising, Eichstätt, Regensburg15836–15 Oct
Breisgau158314–23 Oct
Hildesheim163116–25 Mar
Jülich-Berg15833–12 Nov
Köln, Aachen15834–13 Nov
Münster, Cleve158318–27 Nov
Mainz158312–21 Nov
Minden16682–11 Feb
Paderborn158517–26 Jun
Pfalz-Neuburg161514–23 Dec
Protestant States170019–28 Feb
Preußen161023 Aug–1 Sep
Schlesien, Lausitz158413–22 Jan
Trier15835–14 Oct
Würzburg15835–14 Nov
Westfalen15842–11 Jul
Greece192316–28 Feb
This change was not accepted by the churches of Greece, but the “revised Julian calendar” they did adopt results in no conflicts with the Gregorian calendar until the year 2800. This difference is thus of little concern to most genealogists. However, a few bishops rejected even the revised Julian calendar and continued to use the older Julian calendar, causing a schism in the Church of Greece.
Hungary, Republic of158722–30 Oct
tbd This applies at least to the western third of what is now Hungary. Following a long series of conflicts, by 1541 the west remained under Hapsburg control, the middle third was ruled by the Ottoman Empire, and the eastern third remained independent but eventually became a vasel state of the Ottoman Empire.
Ireland, Republic of17523–13 Sep
Israel1917(see note)
Prior to 1917, the area now known as Israel was ruled by Turkey, and would have used the Islamic or modified Julian calendars used by Turkey. In 1917, England gained dominion so the Gregorian Calendar was in use. There is no official date of conversion.

Israel gained its own sovereignty on 5 May 1948. Since that time, the official calendar has been the Jewish Calendar, but the Gregorian Calendar is maintained for convenience, and official records show dates using both calendars.
Italy15825–14 Oct
Florence, Pisa174921–31 Dec
Japan replaced the traditional lunisolar calendar with the Gregorian calendar on 1 Jan 1873. The year can be represented either in the Common Era, the Japanese era (based on the reign of each emperor; for example, the adoption of the Gregorian calendar was in the year “Meiji 6.”), or, prior to the end of World War II, an “imperial“ year (based on the mythical founding of Japan in 660 b.c.e.). The Common Era year 1873 would have been the imperial year 2533.
Korea replaced the traditional lunisolar calendar with the Gregorian calendar on 1 Jan 1896. The year can be represented either in the Common Era, the Korean era (based on Korean dynasties), or the Danji year (based on the mythical founding of Korea in 2333 b.c.e.). The Common Era year 1896 would have been the Danji year 4229.
Latvia19182–14 Feb
tbd Reverted to Julian in 1796?
Lithuania1584, 1915(see note)
After establishment of the Polish-Lithuanian Commonwealth in 1569, the Grand Duchy of Lithuania continued using the Julian Calendar. It didn't adopt the Gregorian calendar until 1584, dropping 11–20 January. In 1795, most of Lithuania (the provinces of Vilna, Grodno, Kovno, Mohilev, Vitebsk, and Minsk) was transferred to Russia and the Julian Calendar was reinstated on 1 Jan 1800. The rest of Lithuania was transferred to Prussia (now parts of Germany, Poland, and Russia) and continued using the Gregorian Calendar. With the German occupation of (Russian) Lithuania in 1915, the calendar was changed back to the Gregorian, dropping the days 16–28 Nov.
Luxembourg158215–24 Dec
Macedonia, Republic of tbdtbd
Mexico1582, 1697(n/a)
Large parts of modern Mexico were conquered by Spain in two distinct conquests: the first was of the Aztec Empire during 1519–1521, the second was of the Maya in the Yucatán by 1697. After subjugation, official dates would have been recorded in the calendar used by Spain. During the first years after the Aztec conquest, this would have been Julian, converting to Gregorian with the rest of Spain in 1582. The conquest of the Maya was completed after the change to the Gregorian.

Prior to the conquests, the Aztec or Mayan calendars would have been used throughout these areas. The Mayan calendar is still used in some Mayan communities. Other calendars may also have been in use in other areas of Mesoamerica.
Antwerpen158221–30 Dec
Artois, Brabant, Zeeland158215–24 Dec
tbd Zeeland may have lost 22–31 Dec 1583.
Drenthe, Friesland17011–11 Jan
tbd Drenthe may have lost 1–11 May 1701.
Gelderland, Zutphen17001–11 Jul
Groningen15831–10 Mar
Groningen reverted to the Julian calendar on 19 Nov 1594, with the following day being 10 Nov 1594 in the Julian calendar.
Holland158222–31 Dec
tbd They may have lost 2–11 Jan 1583 instead.
Köln15824–13 Nov
Limburg158222–31 Dec
tbd Limburg may have used the French Revolution calendar from 1796 to 1805 (See France.)
Overijssel, Ultrecht17001–11 Dec
Norway170019–28 Feb
Norway was a part of Denmark at this time.
Poland15825–14 Oct
Prusija161023 Aug–1 Sep
Prusija was the germanic state of Preußen at the time that Poland switched.
Portugal15825–14 Oct
Puerto Rico15825–14 Oct
tbd There are a number of different areas with different dates of adoption, but these are unclear and sometimes in conflict.
Russia19181–13 Feb
Prior to 1700, Russia used years based on the mythical creation of the world. In the year 7208 in this system (1699 c.e.), Peter the Great announced the adoption of the Julian Calendar, effective 1 Jan 1700. This calendar was used until the revolution in 1918.

Although the 1918 date above is “official,” Russia was in the middle of a civil war. The “White” forces continued to use the Julian Calendar, while the “Red” forces used the Gregorian, so the calendar in question would vary by location, and even by who controlled the area. Some areas changed hands many times, and the eastern areas of Russia may not have changed until around 1920.
San Marinotbdtbd
Savoy158210–19 Dec
Spain15825–14 Oct
Sweden175318–28 Feb
Sweden actually made an abortive attempt to change in a gradual way. The idea was to simply drop the 11 leap days from 1700 through 1740. This would have brought the calendar into alignment over time (avoiding the economic and legal problems of loosing a block of days) but it would have had the cost of remaining out-of-sync with the rest of Europe by a non-static number of days (with the resultant confusion).

However, poor administration resulted in not removing the leap days from 1704 and 1708. This prompted King Charles XII to abandon the plan, and to revert to the Julian Calendar (rather than simply jumping to the Gregorian). This was done in 1712 and required the addition of a day to replace the one that was dropped in 1700. Thus Sweden had the unique event of a second leap day on 30 Feb 1712.
Switzerland officially recognizes four languages, German, French, Italian and Romansh. The latter is spoken only in Graubünden. Since some of the cantons have more than one offical language, and the names may have varied between languges, the names below are shown in all appropriate languages, separated by a slash (/).

tbd I don't have any information on the Cantons of Aargau, Graubünden/Grischun/Grigioni, Jura, Ticino, or Vaud.
Appenzell Ausserrhoden, Appenzell Innerrhoden, Glarus, St. Gallen1724tbd
Appenzell was divided into the half-cantons listed after the Protestant Reformation in 1597.
Basel-Stadt, Basel-Landschaft158321–30 Oct
Basel was divided into the half-cantons listed after a revolt in 1833.
tbd Basel may have changed in 1701, losing 1–11 Jan.
Bern/Berne, Genève, Neuchâtel, Schaffhausen, Thurgau, Zürich17011–11 Jan
Fribourg/Freiburg, Luzern, Schwyz, Solothurn, Uri, Zug158412–21 Jan
Nidwalden, Obwalden1584tbd
These two half-cantons are also known under the regional name of Unterwalden
Valais/Wallis16551–10 Mar
Turkey, Republic of1917, 1926(see note)
The Ottoman Empire used the Islamic calendar. The Julian Calendar was introduced 1 Mar 1789 but the Islamic calendar was also maintained, giving the empire two official calendars. In addition, the year for the Julian Calendar reflected the Islamic year, not the years of the Common Era.

In 1334 (1917 c.e.) the day adjustment of the Gregorian Calendar was applied to the Julian calendar, losing the days 17–28 Feb, but the year still began on 1 Mar until it was moved to 1 Jan in 1335 (1918 c.e.).

In 1340 (1925 c.e.) the Common Era was adopted for the year numbers, so that 31 Dec 1340 was followed by 1 Jan 1926. The Islamic Calendar was also dropped as an official calendar at this time.
Ukraine1569(see note)
From 1386, most of the Ukrainian territory was under the rule of the Grand Duchy of Lithuania and used the Julian Calendar. In 1569, large parts of Ukraine were moved to Polish rule, and would have used the Gregorian calendar in use by Poland. However, by 1651, Ukraine became an autonomous duchy under Russian protection, but I don't know if the calendar was changed back to the Julian during this period. For a brief period from 1917 to 1921, Ukraine was an independent nation, until it became a founding Republic of the Soviet Union, at which time it would certainly have used the Gregorian calendar.
United Kingdom17523–13 Sep
This includes England, as well as Guernsey, Jersey, Northern Ireland, Isle of Man, and Wales. Note that Gibralter and Scotland require extra notation.
Gibraltar1582, 1752(see note)
Gibraltar was ruled by Spain until 1713, and would have changed to the Gregorian Calendar with Spain, losing 5–14 Oct 1582. In 1713 it was ceded to England, and probably reverted back to the Julian Calendar until England converted to the Gregorian, losing 3–13 Sep 1752.
Scotland17523–13 Sep
There is some confusion as to when Scotland changed to the Gregorian Calendar. However, this may be caused by confusion on what the Gregorian Calendar is. I've noted that at least one of Scotland's government WWW sites talks about the “Scots Gregorian” calendar being adjusted at the same time as the “English Julian.” The problem is that adjusting the first day of the year (in 1600 for Scotland) does not make it a Gregorian Calendar — numerous other countries changed the first day of the year well before the Gregorian adjustment was first announced, and this change wasn't even stipulated by Pope Gregory. Thus I believe the 1752 date is correct.
United States of America
Prior to the establishment of European colonies in what is now the United States, the various tribal nations that occupied the land had their own traditions for tracking time. These traditions would have continued after European settlement for the various nations that remained independent.
Alaska18677–17 Oct
This change occurred due to the transfer from Russia (which still used the Julian calendar in 1867) to U.S. ownership. Although the calendar was out of date by 12 days, only 11 were skipped and the day of the week was repeated. That is, Friday, 6 Oct 1867 was followed by Friday 18 Oct 1867. The extra day was realized by moving the International Date Line from east of Alaska to its current location west of Alaska. (Movement of the date line was to keep Alaska on the same "side" of the date line as the United States rather than Russia.)
English Colonies17523–13 Sep
The eastern seaboard and inland areas (13 colonies) and all or part of the current states of Washington and Oregon.
French Colonies1699(n/a)
Mississippi valley. This date is much later than the date of France's changeover, since the first European settlement in the Mississippi Valley wasn't established until 1 May 1699.
Spanish Colonies15825–14 Oct
All or part of the current states of Arizona, California, Florida, Nevada, New Mexico, and Texas.
Vatican City15825–14 Oct
Vatican City is all that remains of the much larger Papal States in Italy that were ruled by the Pope. As such, they would have changed the calendar with the papal decree.