Gregorian calendar

====Adoption by country====
{{hatnote|This is a brief summary. For a comprehensive table, see [[List of adoption dates of the Gregorian calendar by country]]}}
{| class="wikitable"
! Year
! Country/-ies/Areas 
|-
| 1582
| [[Spain]], [[Portugal]], [[France]], [[Polish-Lithuanian Commonwealth]], [[Italy]], Catholic [[Low Countries]], [[Luxembourg]], and colonies thereof
|-
| 1584
| [[Kingdom of Bohemia]], some Catholic [[Swiss cantons]]{{efn|name="CH"|In the [[Old Swiss Confederacy]], [[Helvetic Republic]], or [[Switzerland]], adoptions were made between 1584 and 1811. Some Catholic cantons switched in 1584, some Protestant in 1700/1701. For a complete list see [[List of adoption dates of the Gregorian calendar per country]].}}
|-
| 1610
| [[Prussia]]
|-
| 1648
| [[Alsace]]
|-
| 1682
| [[Strasbourg]]
|-
| 1700
| Protestant [[Low Countries]], [[Norway]], [[Denmark]], some Protestant [[Swiss cantons]]{{efn| name="CH"}}
|-
| 1752
| [[Kingdom of Great Britain|Great Britain]], [[Kingdom of Ireland|Ireland]], and the [[British Empire#"First" British Empire (1707–1783)|"First" British Empire (1707–1783)]]
|-
| 1753
| [[Sweden]] and [[Finland]]
|-
| 1873
| [[Japan]]
|-
| 1875
| [[Egypt]]
|-
| 1896
| [[Korea]]
|-
| 1912
| [[China]], [[Albania]]
|-
| 1915
| [[Latvia]], [[Lithuania]]
|-
| 1916
| [[Bulgaria]]
|-
| 1917
| [[Ottoman Empire]]
|-
| 1918
| [[Ukraine]], [[Russia]], [[Estonia]]
|-
| 1919
| [[Romania]], [[Yugoslavia]]{{efn|1919 in the regions comprising the former Kingdoms of Serbia and Montenegro (present-day Kosovo, Montenegro, Serbia and North Macedonia). The western and northern regions of what became Yugoslavia were already using the Gregorian calendar. For example, most of [[Slovenia]] adopted the Gregorian calendar at the same time as [[Austria]] in 1583. Coastal [[Croatia]], which was at the time ruled by [[Venice]], adopted the Gregorian calendar in 1582. Inland [[Croatia]], ruled by the [[House of Habsburg|Habsburgs]], adopted it in 1587 along with Hungary. The Gregorian calendar was used in [[Bosnia and Herzegovina]] since the 16th century by the [[Catholic Church|Catholic]] population and was formally adopted for government use in 1878 following occupation by [[Austria-Hungary]].}}
|-
| 1923
| [[Greece]]
|-
| 1926
| [[Turkey]] ([[common era]] years; Gregorian dates in use since 1917 Ottoman adoption)
|-
| 2016
| [[Saudi Arabia]]
|}