GMT
Greenwich Mean Time
GMT +0
IST
Iran Standard Time
GMT +3:30

Time Difference

Greenwich Mean Time is 3 hours and 30 minutes behind Iran Standard Time
9:00 pm21:00 in GMT is 12:30 am00:30 in IST

GMT to IST call time
Best time for a conference call or a meeting is between 8am-2:30pm in GMT which corresponds to 11:30am-6pm in IST

9:00 pm21:00 Greenwich Mean Time (GMT). Offset UTC 0:00 hours
12:30 am00:30 Iran Standard Time (IST). Offset UTC +3:30 hours

9:00 pm21:00 GMT / 12:30 am00:30 IST

GMT IST
12am (midnight) 3:30 am
1am 4:30 am
2am 5:30 am
3am 6:30 am
4am 7:30 am
5am 8:30 am
6am 9:30 am
7am 10:30 am
8am 11:30 am
9am 12:30 pm
10am 1:30 pm
11am 2:30 pm
12pm (noon) 3:30 pm
1pm 4:30 pm
2pm 5:30 pm
3pm 6:30 pm
4pm 7:30 pm
5pm 8:30 pm
6pm 9:30 pm
7pm 10:30 pm
8pm 11:30 pm
9pm 12:30 am
10pm 1:30 am
11pm 2:30 am
0:00 3:30
1:00 4:30
2:00 5:30
3:00 6:30
4:00 7:30
5:00 8:30
6:00 9:30
7:00 10:30
8:00 11:30
9:00 12:30
10:00 13:30
11:00 14:30
12:00 15:30
13:00 16:30
14:00 17:30
15:00 18:30
16:00 19:30
17:00 20:30
18:00 21:30
19:00 22:30
20:00 23:30
21:00 0:30
22:00 1:30
23:00 2:30

Greenwich Mean Time

Offset: GMT is 0 hours ahead Greenwich Mean Time (GMT) and is used in Europe

Countries: It is used in following countries: Burkina Faso, Côte d'Ivoire, Britain (UK), Guernsey, Ghana, Greenland, Gambia, Guinea, Guinea-Bissau, Ireland, Isle of Man, Iceland, Jersey, Liberia, Mali, Mauritania, St Helena, Sierra Leone, Senegal, Sao Tome & Principe, Togo

Principal Cities: The largest city in the GMT timezone is London from United Kingdom with population about 7.557 million people. Other major cities in the area are Abidjan, Dakar, Grand Dakar, Accra

Greenwich Mean Time (GMT) originally referred to the mean solar time at the Royal Observatory in Greenwich, London. It is now often used to refer to Coordinated Universal Time (UTC) when this is viewed as a time zone, and in casual use for the most parts it is the same. In military GMT is known as Zulu time.Greenwich Mean Time was the same as Universal Time (UT), until the introduction of UTC in 1972 a standard astronomical concept used in many technical fields.

GMT Time Zone Geo Map
GMT timezone map

GMT representations, usage and related time zones

W3C/ISO-8601: International standard covering representation and exchange of dates and time-related data
  • Z - is the zone designator for the zero UTC/GMT offset, also known as 'Zulu' time
  • +00 - basic short
  • +0000 - basic
  • +00:00 - extended
Email/RFC-2822: Internet Message Format Date Standard, typically used for timestamps in email headers
  • +0000 - sign character (+) followed by a four digit time providing hours (00) and minutes (00) of the offset. Indicates zero hour and zero minutes time differences of the zero meridian.
Military/NATO: Used by the U.S. military, Chinese military and others
  • Zulu - Military abbreviation for GMT
  • Z - short form of 'Zulu'
IANA/Olson: Reflects GMT time zone boundaries defined by political bodies, primarily intended for use with computer programs and operating systems
  • Africa/Abidjan
  • Africa/Accra
  • Africa/Bamako
  • Africa/Banjul
  • Africa/Bissau
  • Africa/Conakry
  • Africa/Dakar
  • Africa/Freetown
  • Africa/Lome
  • Africa/Monrovia
  • Africa/Nouakchott
  • Africa/Ouagadougou
  • Africa/Sao_Tome
  • Africa/Timbuktu
  • America/Danmarkshavn
  • Atlantic/Reykjavik
  • Atlantic/St_Helena
  • Eire
  • Etc/GMT
  • Etc/GMT+0
  • Etc/GMT-0
  • Etc/GMT0
  • Etc/Greenwich
  • Europe/Belfast
  • Europe/Dublin
  • Europe/Guernsey
  • Europe/Isle_of_Man
  • Europe/Jersey
  • Europe/London
  • GB
  • GB-Eire
  • GMT
  • GMT+0
  • GMT-0
  • GMT0
  • Greenwich
  • Iceland
GMT Abbreviation: Several time zones share GMT abbreviation and it could refer to these time zones
  • Greenwich Mean Time - UTC +0
  • GMT+03:00 - UTC +3
  • GMT - UTC +1
  • GMT+06:00 - UTC +6
  • GMT-01:00 - UTC -1
  • GMT+11:00 - UTC +11
Time zones with the GMT +0 offset:
  • EGST - Eastern Greenland Summer Time
  • GMT - Greenwich Mean Time
  • WET - Western European Time
  • AZOST - Azores Summer Time
  • UTC - Universal Time Coordinated
  • WT - Western Sahara Standard Time
  • Z - Zulu Time Zone

Iran Standard Time

Offset: IST is 3 hours and 30 minutes ahead Greenwich Mean Time (GMT) and is used in Asia

Countries: It is used in following countries: Israel

Principal Cities: The largest city in the IST timezone is Jerusalem from Israel with population about 801,000 people. Other major cities in the area are West Jerusalem, Haifa, Tel Aviv, Ashdod

IST representations, usage and related time zones

W3C/ISO-8601: International standard covering representation and exchange of dates and time-related data
  • +0330 - basic
  • +03:30 - extended
Email/RFC-2822: Internet Message Format Date Standard, typically used for timestamps in email headers
  • +0330 - sign character (+) followed by a four digit time providing hours (03) and minutes (30) of the offset. Indicates three hour and thirty minutes time differences to the east of the zero meridian.
IST Abbreviation: Several time zones share IST abbreviation and it could refer to these time zones
  • India Standard Time - UTC +5:30
  • Irish Standard Time - UTC +1
  • Israel Standard Time - UTC +2
  • Iran Standard Time - UTC +3:30