List of adoption dates of the Gregorian calendar by country

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This is a list of adoption dates of the Gregorian calendar by country. For explanation, see the article about the Gregorian calendar.

Except where stated otherwise, the transition was a move by the civil authorities from the Julian to the Gregorian calendar. In religious sources it could be that the Julian calendar was used for a longer period of time, in particular by Protestant and Eastern Orthodox churches. The historic area does not necessarily match the present-day area or country. The column "Present country" only provides a logic search entry. With a few exceptions, the former colonies of European powers are not shown separately.

There are only four countries which have not adopted the Gregorian calendar: Ethiopia (Ethiopian calendar), Nepal (Vikram Samvat and Nepal Sambat), Iran and Afghanistan (Solar Hijri calendar).^[1] Thailand has adopted the Gregorian calendar for days and months, but uses its own era for years: the Buddhist era. The partially recognized Republic of China (Taiwan) also uses its own era, the Minguo era. ^{[citation needed]}