Iran Standard Time

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Time in the Middle East
    UTC+02:00 Eastern European Time

Eastern European Time /
Israel Standard Time
Eastern European Summer Time /
Israel Summer (Daylight) Time
    UTC+03:00 Further-eastern European Time
Arabia Standard Time
Iran Standard Time
Iran Daylight Time
    UTC+04:00 Gulf Standard Time
Light colors indicate where standard time is observed all year; dark colors indicate where daylight savings is observed.

Iran Standard Time (IRST) or Iran Time (IT) is the time zone used in Iran. 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 (called Iran Daylight Time or IRDT).[1][2] It was reintroduced from 21 March 2008.

Daylight Saving Transitions Dates[edit]

Iran is unusual in that the dates of DST transitions aren't based on a rule such as the third Monday in September.
So in most countries, DST transitions occur on the same weekday every year, but not in Iran.[3]

Sat, Mar 22, 12:00 AM
Mon, Sep 22, 12:00 AM
Sun, Mar 22, 12:00 AM
Tue, Sep 22, 12:00 AM
Mon, Mar 21, 12:00 AM
Wed, Sep 21, 12:00 AM
Wed, Mar 22, 12:00 AM
Fri, Sep 22, 12:00 AM
Thu, Mar 22, 12:00 AM
Sat, Sep 22, 12:00 AM

Time zone changes[edit]

Period in use Time offset from GMT Name of Time
1800 – 1946 UTC+03:25:44 Iran Standard Time (IRST)
1947 – 1977 UTC+03:30 Iran Standard Time (IRST)
1977 – 1979 UTC+04:00
Iran Standard Time (IRST)
Iran Daylight Time (IRDT)
1979 – 1980 UTC+03:30
Iran Standard Time (IRST)
Iran Daylight Time (IRDT)
1981 – 1990 UTC+03:30 Iran Standard Time (IRST)
1991 – 2005 UTC+03:30
Iran Standard Time (IRST)
Iran Daylight Time (IRDT)
2006 – 2007 UTC+03:30 Iran Standard Time (IRST)
2008 – present UTC+03:30
Iran Standard Time (IRST)
Iran Daylight Time (IRDT)

IANA time zone database[edit]

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


  1. ^ "Iran will not observe DST". 20 March 2007. Retrieved 9 May 2010. 
  2. ^ "Time zone and daylight saving time for Iran – Tehran between 2010 and 2019". Retrieved 9 May 2010. 
  3. ^ "Time Changes in Tehran over the years".