GMT
Greenwich Mean Time
GMT +0
HST/HDT
Hawaii Standard Time
GMT -10
HDT automatically adjusted to HST time zone, that is in use

Time Difference

Greenwich Mean Time is 10 hours ahead of Hawaii Standard Time
So 2:30 pm14:30 in GMT is 4:30 am04:30 in HST

2:30 pm14:30 Greenwich Mean Time (GMT). Offset UTC 0:00 hours
4:30 am04:30 Hawaii Standard Time (HST). Offset UTC -10:00 hours

2:30 pm14:30 GMT / 4:30 am04:30 HST

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

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+06:00 - UTC +6
  • GMT+03:00 - UTC +3
  • GMT - UTC +1
  • GMT+04:00 - UTC +4
  • GMT-10:00 - UTC -10

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
  • GMT - GMT


Hawaii Daylight Time

Offset: HDT is 9 hours behind Greenwich Mean Time (GMT) and is used in Pacific

Countries: It is used in following countries: United States

Daylight Saving: Hawaii Daylight Time (HDT) is a daylight saving/summer timezone, however during winter some places switch clocks for one hour back and observe Hawaii Standard Time (HST).

Start: Hawaii Daylight Time (HDT) started and clocks were set one hour forward on Sunday, 08 March 2020, at 2:00 (2:00 am) local time.

End: Hawaii Daylight Time (HDT) ends and clocks are set one hour back on Sunday, 01 November 2020, at 2:00 (2:00 am) local time.

HDT representations, usage and related time zones

W3C/ISO-8601: International standard covering representation and exchange of dates and time-related data
  • -09 - basic short
  • -0900 - basic
  • -09:00 - extended

Email/RFC-2822: Internet Message Format Date Standard, typically used for timestamps in email headers
  • -0900 - sign character (-) followed by a four digit time providing hours (09) and minutes (00) of the offset. Indicates nine hour and zero minutes time differences to the west of the zero meridian.

Military/NATO: Used by the U.S. military, Chinese military and others
  • Victor - Military abbreviation for HDT
  • V - short form of 'Victor'

IANA/Olson: Reflects HDT time zone boundaries defined by political bodies, primarily intended for use with computer programs and operating systems
  • America/Adak
  • America/Atka
  • US/Aleutian

Time zones with the GMT -9 offset:

  • AKST - Alaska Standard Time
  • AHDT - Alaska-Hawaii Daylight Time
  • HADT - Hawaii-Aleutian Daylight Time
  • YST - Yukon Standard Time
  • GAMT - Gambier Time
  • HDT - Hawaii Daylight Time
  • V - Victor Time Zone
  • -09 -