GMT to HDT Converter
The United Kingdom is on summer time: BST (UTC+1) until Sun, Oct 25.
Iceland and Ghana stay on GMT (UTC+0).
HDT is not used on this date
This converter keeps HDT at UTC−9. Honolulu uses HST (UTC−10) on this date. Open the HST converter, or choose Honolulu, Pearl City, or Hilo for city-specific time.Start by searching for a time zone, city, or town.
Add one or more places to compare local times, adjust the date, and share the result.
Quick answers
Selected conversion
12:00 pm12:00 GMT (UTC+0), Oct 18, 2026 = 3:00 am03:00 HDT (UTC-9), Oct 18, 2026
GMT is 9 hours ahead of HDT.
GMT and HDT examples
These examples always use GMT (UTC+0) and HDT (UTC-9). They stay the same when you change the date or time above. The selected conversion may differ when daylight saving time applies.
GMT is 9 hours ahead of HDT.
How the time difference changes
GMT is 9 hours ahead of HDT year-round.
Working hours of 9:00 am to 6:00 pm in GMT correspond to 12:00 am to 9:00 am in HDT.Working hours of 09:00 to 18:00 in GMT correspond to 00:00 to 09:00 in HDT.
Compare GMT time with HDT time, including current local time, UTC offsets, time difference, daylight saving changes, working hours, and shareable meeting times.
Time Difference
Greenwich Mean Time is 9 hours ahead of Hawaii Daylight Time.
12:00 pm12:00 in GMT is 3:00 am03:00 in HDT
GMT to HDT call time
Best time for a conference call or a meeting is between 5:30pm-6:30pm17:30-18:30 in GMT which corresponds to 8:30am-9:30am08:30-09:30 in HDT. Their 9am–6pm09:00–18:00 working hours do not overlap; this is a suggested compromise.
12:00 pm12:00 Greenwich Mean Time (GMT). Offset UTC 0:00 hours
3:00 am03:00 Hawaii Daylight Time (HDT). Offset UTC -9:00 hours
12:00 pm12:00 GMT / 3:00 am03:00 HDT
Choose an hour to update the converter. Day labels such as “next day” or “+1” are relative to the selected date in the first column. Use Up and Down arrow keys, Home or End to move between hours, then Enter or Space to select.
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Greenwich Mean Time
Offset: GMT is the same as Greenwich Mean Time (GMT).
Countries using this time zone: Antarctica, Burkina Faso, Gambia, Ghana, Greenland, Guernsey, Guinea, Guinea-Bissau, Iceland, Ireland, Isle of Man, Ivory Coast, Jersey, Liberia, Mali, Mauritania, Morocco, Saint Helena, São Tomé and Príncipe, Senegal, Sierra Leone, Togo, United Kingdom, Western Sahara
Principal Cities: The largest city in the GMT time zone is London in the United Kingdom, with about 8.962 million people. Other major cities in this time zone include Abidjan, Bamako, Casablanca, Dakar.
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 the two are the same. In the military, GMT is known as Zulu time. Greenwich Mean Time was the same as Universal Time (UT), a standard astronomical concept used in many technical fields, until the introduction of UTC in 1972.
Today the lighter areas are on UTC+1 (British Summer Time, Irish Standard Time).
GMT representations, usage and related time zones
- Z - is the zone designator for the zero UTC/GMT offset, also known as 'Zulu' time
- +00 - basic short
- +0000 - basic
- +00:00 - extended
- +0000 - sign character (+) followed by a four digit time providing hours (00) and minutes (00) of the offset. Indicates the zero UTC/GMT offset.
- Zulu - Military abbreviation for GMT
- Z - short form of 'Zulu'
- 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
- EGST - Eastern Greenland Summer Time
- GMT - Greenwich Mean Time
- WET - Western European Time
- AZOST - Azores Summer Time
- UTC - Coordinated Universal Time
- WT - Western Sahara Standard Time
- Z - Zulu Time Zone
Hawaii Daylight Time
Offset: HDT is 9 hours behind Greenwich Mean Time (GMT).
Countries using this time zone: United States
Today all shaded areas are on HDT.
HDT representations, usage and related time zones
- -09 - basic short
- -0900 - basic
- -09:00 - extended
- -0900 - sign character (-) followed by a four digit time providing hours (09) and minutes (00) of the offset. Indicates an offset of nine hours to the west of the zero meridian.
- Victor - Military abbreviation for HDT
- V - short form of 'Victor'
- America/Adak
- America/Atka
- US/Aleutian
- AKST - Alaska Standard Time
- AHDT - Alaska-Hawaii Daylight Time
- HADT - Hawaii-Aleutian Daylight Time
- GAMT - Gambier Time
- HDT - Hawaii Daylight Time
- V - Victor Time Zone