Iran Standard Time (IRST) or Iran Time (IT) is the

time zone A time zone is an area which observes a uniform standard time for legal, commercial and social purposes. Time zones tend to follow the boundaries between countries and their subdivisions instead of strictly following longitude, because it ...

used in

Iran Iran, officially the Islamic Republic of Iran, and also called Persia, is a country located in Western Asia. It is bordered by Iraq and Turkey to the west, by Azerbaijan and Armenia to the northwest, by the Caspian Sea and Turkmeni ...

. Iran uses a UTC offset UTC+03:30. IRST is defined by the 52.5 degrees east meridian, the same meridian which defines the Iranian calendar and is the official meridian of Iran. Between 2005 and 2008, by decree of President Mahmoud Ahmadinejad, Iran did not observe daylight saving time (DST) (called ''Iran Daylight Time'' or ''IRDT''). It was reintroduced from 21 March 2008. On 21 September 2022, Iran abolished DST and now observes standard time year-round.

Daylight Saving Time transitions

The dates of DST transitions in Iran were based on the

Solar Hijri calendar The Solar calendar ( fa, گاه‌شماری هجری خورشیدی, Gâhšomâri-ye Xoršidi; ps, لمريز لېږدیز کلیز, lamrez legdez kalhandara; ku, ڕۆژژمێری کۆچیی ھەتاوی, Salnameya Koçberiyê) is a solar c ...

, the official calendar of

, which is in turn based on the March equinox (

Nowruz Nowruz ( fa, نوروز, ; ), zh, 诺鲁孜节, ug, نەۋروز, ka, ნოვრუზ, ku, Newroz, he, נורוז, kk, Наурыз, ky, Нооруз, mn, Наурыз, ur, نوروز, tg, Наврӯз, tr, Nevruz, tk, Nowruz, ...

) as determined by astronomical calculation at the meridian for Iran Standard Time (52.5°E or GMT+3.5h). This resulted in the unique situation wherein the dates of DST transitions didn't fall on the same weekday each year as they do in most other countries. DST started in Iran at 24:00 on 1 Farvardin, which corresponds to either 20 or 21 March in the

Gregorian calendar The Gregorian calendar is the calendar used in most parts of the world. It was introduced in October 1582 by Pope Gregory XIII as a modification of, and replacement for, the Julian calendar. The principal change was to space leap years dif ...

, depending on the precise timing of the equinox. (This is equivalent to 00:00 on 2 Farvardin, either 21 or 22 March.) Clocks moved forward at that time to 01:00 on 2 Farvardin (21 or 22 March). This spring change took place at the end of the day of

, which is the Iranian New Year's Day and the most important festival in Iranian culture. DST likewise ended in Iran at 24:00 on 30 Shahrivar, which corresponds to either 20 or 21 September. (Equivalently, at 00:00 on 31 Shahrivar, either 21 or 22 September). Clocks moved backward to 23:00 on 30 Shahrivar (20 or 21 September).

Recent and upcoming dates

Time zone changes

IANA time zone database

The IANA time zone database contains one zone for Iran in the file zone.tab, named Asia/Tehran.

References

Time in Iran Time zones {{iran-stub

Daylight Saving Time transitions

Recent and upcoming dates

Time zone changes

IANA time zone database

See also

References