| The Gregorian calendar is internationally the most widely used civil calendar. It is named after Pope Gregory XIII, who introduced it in October 1582. |
| It was a refinement to the Julian calendar involving an approximately 0.002% correction in the length of the calendar year. The motivation for the reform was to stop the drift of the calendar with respect to the equinoxes and solstices—particularly the northern vernal equinox, which helps set the date for Easter. Transition to the Gregorian calendar would restore the holiday to the time of the year in which it was celebrated when introduced by the early Church. The reform was adopted initially by the Catholic countries of Europe. Protestants and Eastern Orthodox countries continued to use the traditional Julian calendar and adopted the Gregorian reform, one by one, after a time, at least for civil purposes and for the sake of convenience in international trade. The last European country to adopt the reform was Greece, in 1923. Many (but not all) countries that have traditionally used the Julian calendar, or the Islamic or other religious calendars, have come to adopt the Gregorian calendar for civil purposes. |
| Gregorian years are identified by consecutive year numbers. The cycles repeat completely every 146,097 days, which equals 400 years. Of these 400 years, 303 are regular years of 365 days and 97 are leap years of 366 days. A mean calendar year is 365 97/400 days = 365.2425 days, or 365 days, 5 hours, 49 minutes and 12 seconds. |
| . . . . the new calendar was implemented on the date specified . . . with Julian Thursday, 4 October 1582, being followed by Gregorian Friday, 15 October 1582. |
| |
| Months |
| The Gregorian calendar continued to employ the Julian months, which have Latinate names and irregular numbers of days: |
- January (31 days), from Latin mēnsis Iānuārius, "Month of Janus", the Roman god of gates, doorways, beginnings and endings
- February (28 days in common and 29 in leap years), from Latin mēnsis Februārius, "Month of the Februa", the Roman festival of purgation and purification, cognate with fever, the Etruscan death god Februus ("Purifier"), and the PIE word for sulfur
- March (31 days), from Latin mēnsis Mārtius, "Month of Mars", the Roman war god
- April (30 days), from Latin mēnsis Aprīlis, of uncertain meaning but usually derived from some form of the verb aperire ("to open") or the name of the goddess Aphrodite
- May (31 days), from Latin mēnsis Māius, "Month of Maia", a Roman vegetation goddess whose name is cognate with Latin magnus ("great") and English major
- June (30 days), from Latin mēnsis Iūnius, "Month of Juno", the Roman goddess of marriage, childbirth, and rule
- July (31 days), from Latin mēnsis Iūlius, "Month of Julius Caesar", the month of Caesar's birth, instituted in 44 BC as part of his calendrical reforms
- August (31 days), from Latin mēnsis Augustus, "Month of Augustus", instituted by Augustus in 8 BC in agreement with July and from the occurrence during the month of several important events during his rise to power
- September (30 days), from Latin mēnsis september, "seventh month", from its position in the Roman calendar before 153 BC
- October (31 days), from Latin mēnsis octōber, "eighth month", from its position in the Roman calendar before 153 BC
- November (30 days), from Latin mēnsis november, "ninth month", from its position in the Roman calendar before 153 BC
- December (31 days), from Latin mēnsis december, "tenth month", from its position in the Roman calendar before 153 BC
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| [ Wikipedia - Christian Calendar ] |
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| List of adoption dates of the Gregorian calendar per country |
| From Wikipedia, the free encyclopedia |
| This is a list of adoption dates of the Gregorian calendar per country. For explanation, see the article about the Gregorian calendar. |
| If not stated otherwise, it concerns the transition from the Julian to the Gregorian calendar by the civil authorities. In religious sources it could be that the Julian calendar was used for a longer period of time, in particular on the Protestant and Eastern Orthodox side. The historic area does not necessarily match the present-day area or country. The column 'present country' only provides a logic search entry. |
| This table is sorted by date. To see list sorted by other columns see: List of adoption dates of the Gregorian calendar per country |
| Present Country
| Historic Area
| After
| Follows
| Particulars |
| Italy |
|
1582-10-04 |
1582-10-15 |
|
| Poland |
Poland |
1582-10-04 |
1582-10-15 |
local resistance |
| Portugal |
Portuguese Empire |
1582-10-04 |
1582-10-15 |
|
| Spain |
Spanish Empire |
1582-10-04 |
1582-10-15 |
|
| France |
France |
1582-12-09 |
1582-12-20 |
without Alsace and Lorraine |
| France |
Sedan |
1582-12-09 |
1582-12-20 |
|
| Netherlands |
Brabant |
1582-12-14 |
1582-12-25 |
edict of Francis, Duke of Anjou followed |
| Belgium |
Flanders |
1582-12-14 |
1582-12-25 |
edict of Francis, Duke of Anjou followed |
| Netherlands |
States General |
1582-12-14 |
1582-12-25 |
edict of Francis, Duke of Anjou followed |
| Netherlands |
Zeeland |
1582-12-14 |
1582-12-25 |
edict of Francis, Duke of Anjou followed |
| Belgium |
Southern Netherlands |
1582-12-20 |
1582-12-31 |
or one day later; areas under Spanish rule: Artois, occupied Brabant, occupied Flanders, Hainaut, Limburg, Luxemburg, Namur |
| Netherlands |
Holland |
1583-01-01 |
1583-01-12 |
edict of Francis, Duke of Anjou followed later on |
| Belgium |
Liège |
1583-02-10 |
1583-02-21 |
edict of Philip II of Spain followed |
| Netherlands |
Groningen (city) |
1583-03-01 |
1583-03-12 |
edict of Philip II of Spain was: 10 followed by 21 February (proclaimed later) |
| Lithuania |
Grand Duchy of Lithuania |
1585-12-21 |
1586-01-01 |
|
| Netherlands |
Groningen (city) |
1594-11-19 |
1594-11-10 |
return to the Julian calendar |
| Poland |
Duchy of Prussia |
1612-08-22 |
1612-09-02 |
southern Ducal Prussia is now part of Poland |
| Lithuania |
Duchy of Prussia |
1612-08-22 |
1612-09-02 |
north eastern Ducal Prussia is now part of Lithuania |
| Russia |
Duchy of Prussia |
1612-08-22 |
1612-09-02 |
northern Ducal Prussia is now part of Russia |
| Latvia |
Courland |
1617-00-00 |
1617-00-00 |
? |
| Sweden |
Swedish Empire |
1700-02-28 |
1700-03-01 |
incl. Finland |
| Netherlands |
Gelderland |
1700-06-30 |
1700-07-12 |
|
| Netherlands |
Overijssel |
1700-11-30 |
1700-12-12 |
|
| Netherlands |
Utrecht |
1700-11-30 |
1700-12-12 |
|
| Netherlands |
Frisia |
1700-12-31 |
1701-01-12 |
|
| Netherlands |
Groningen (province) |
1700-12-31 |
1701-01-12 |
Stad and Ommelanden |
| Switzerland |
Switzerland, Protestant parts |
1700-12-31 |
1701-01-12 |
Basel, Bern, Mulhouse, Sargans, Schaffhausen, Geneva and Zürich |
| Netherlands |
Drenthe |
1701-04-30 |
1701-05-12 |
|
| Sweden |
Swedish Empire |
1712-02-30 |
1712-03-01 |
incl. Finland; return to the Julian calendar |
| United Kingdom |
British Empire |
1752-09-02 |
1752-09-14 |
|
| Sweden |
Sweden |
1753-02-17 |
1753-03-01 |
incl. Finland |
| Latvia |
Courland |
1796-02-07 |
1796-01-28 |
return to the Julian calendar |
| Lithuania |
Lithuania Governorate |
1800-01-12 |
1800-01-01 |
return to the Julian calendar |
| Latvia |
Courland |
1915-05-12 |
1915-05-25 |
|
| Lithuania |
Kovno and Vilna Governorates |
1915-05-12 |
1915-05-25 |
|
| Latvia |
Livland |
1915-08-22 |
1917-09-05 |
|
| Russia |
Russia |
1918-01-31 |
1918-02-14 |
|
| Estonia |
Estonia |
1918-02-15 |
1918-03-01 |
|
| Greece |
Greece |
1923-02-15 |
1923-03-01 |
except Athos |
| Present Country
| Historic Area
| After
| Follows
| Particulars |
|
| [ Wikipedia - List of adoption dates of the Gregorian calendar per country ] |
|
| See also: |
|
| |
|
| Julian to Gregorian |
 |
| This is a visual example of the official date change from the Julian calendar to the Gregorian. |
[  ] [ Wikipedia - Julian Calendar ] |
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