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

Time Difference

Hawaii Standard Time is 10 hours behind of Greenwich Mean Time
So 1:30 pm13:30 in HST is 11:30 pm23:30 in GMT

1:30 pm13:30 Hawaii Standard Time (HST). Offset UTC -10:00 hours
11:30 pm23:30 Greenwich Mean Time (GMT). Offset UTC 0:00 hours

1:30 pm13:30 HST / 11:30 pm23:30 GMT

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

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, March 8, 2020, at 2:00 (2:00 am) local time.

End: Hawaii Daylight Time (HDT) ends and clocks are set one hour back on Sunday, November 1, 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 -


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

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
  • +00 -