What Is the Gregorian Calendar?
Definition
Gregorian Calendar: The calendar in official use in Türkiye and most of the world. A year has 365 days, a leap year 366; Türkiye adopted it by Law No. 698, from 1 January 1926.
The Gregorian calendar is the calendar in official use in Türkiye and most of the world today. A year has 12 months and 365 days; in leap years February has 29 days and the year has 366. Türkiye adopted it by Law No. 698: the day after 31 December of the Rumi year 1341 became 1 January 1926.
Where it appears in the formulas
The leap year rule: leap year = (year divisible by 4 and not by 100) or (year divisible by 400). The age calculator, the date difference calculator and the day counter count by this rule: 1 January to 31 December 2026, end day included, is 365 days. Dates before 1926 are counted on the Gregorian calendar too.
How it differs from the Hijri calendar
Under Law No. 698 the Islamic lunar (Hijri) calendar stays in use for special purposes. A lunar year is shorter than the solar Gregorian year, so religious holidays fall earlier in the Gregorian calendar each year. The Gregorian calendar replaced the Julian calendar in 1582, under Pope Gregory XIII.