The 344-Year Road to a Global Calendar

The Gregorian reform took effect on Friday 15 October 1582 in Spain, Portugal, the Italian states and Poland-Lithuania, and France followed that December. Catholic states of the Holy Roman Empire switched over the next few years. Protestant and Orthodox countries were in no hurry to accept a reform issued by the Pope.

Protestant Germany and Denmark-Norway changed in 1700, Britain and its empire in 1752 and Sweden in 1753, after its strange experiment that produced a 30 February in 1712. Outside Europe, Japan switched in 1873 as part of the Meiji modernisation, Korea in 1896 and China in 1912.

The Orthodox world came last. Bulgaria changed for civil purposes in 1916, Soviet Russia in February 1918, Romania in 1919 and Greece in 1923. Turkey, which had aligned its Rumi calendar with Gregorian days and months in 1917, adopted Gregorian year numbering from 1 January 1926. Many Orthodox churches still keep the Julian calendar for feasts, which is why Christmas falls on 7 January in Russia and Serbia.

Even now the Gregorian calendar is not universal as a civil calendar. Ethiopia, Nepal, Iran and Afghanistan use their own official calendars, and Saudi Arabia kept the Hijri calendar for official purposes while moving its civil service pay to Gregorian months in 2016. Many other countries use the Gregorian calendar for civil life while religious and traditional calendars set the dates of festivals.