GMT to JST Converter
The United Kingdom is on summer time: BST (UTC+1) until Sun, Oct 25.
Iceland and Ghana stay on GMT (UTC+0).
Quick answers
Selected conversion
12:00 pm12:00 GMT (UTC+0), Oct 4, 2026 = 9:00 pm21:00 JST (UTC+9), Oct 4, 2026
GMT is 9 hours behind JST.
GMT and JST examples
These examples always use GMT (UTC+0) and JST (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 behind JST.
How the time difference changes
GMT is 9 hours behind JST year-round.
Working hours of 9:00 am to 5:00 pm in GMT correspond to 6:00 pm to 2:00 am (next day) in JST.Working hours of 09:00 to 17:00 in GMT correspond to 18:00 to 02:00 (next day) in JST.
Compare GMT time with JST 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 behind Japan Standard Time.
12:00 pm12:00 in GMT is 9:00 pm21:00 in JST
GMT to JST call time
Best time for a conference call or a meeting is between 8am-9am08:00-09:00 in GMT which corresponds to 5pm-6pm17:00-18:00 in JST
12:00 pm12:00 Greenwich Mean Time (GMT). Offset UTC 0:00 hours
9:00 pm21:00 Japan Standard Time (JST). Offset UTC +9:00 hours
12:00 pm12:00 GMT / 9:00 pm21:00 JST
| GMT | JST |
|---|---|
| 12:00am | 9:00am |
| 1:00am | 10:00am |
| 2:00am | 11:00am |
| 3:00am | 12:00pm |
| 4:00am | 1:00pm |
| 5:00am | 2:00pm |
| 6:00am | 3:00pm |
| 7:00am | 4:00pm |
| 8:00am | 5:00pm |
| 9:00am | 6:00pm |
| 10:00am | 7:00pm |
| 11:00am | 8:00pm |
| 12:00pm | 9:00pm |
| 1:00pm | 10:00pm |
| 2:00pm | 11:00pm |
| 3:00pm | 12:00am |
| 4:00pm | 1:00am |
| 5:00pm | 2:00am |
| 6:00pm | 3:00am |
| 7:00pm | 4:00am |
| 8:00pm | 5:00am |
| 9:00pm | 6:00am |
| 10:00pm | 7:00am |
| 11:00pm | 8:00am |
| 00:00 | 09:00 |
| 01:00 | 10:00 |
| 02:00 | 11:00 |
| 03:00 | 12:00 |
| 04:00 | 13:00 |
| 05:00 | 14:00 |
| 06:00 | 15:00 |
| 07:00 | 16:00 |
| 08:00 | 17:00 |
| 09:00 | 18:00 |
| 10:00 | 19:00 |
| 11:00 | 20:00 |
| 12:00 | 21:00 |
| 13:00 | 22:00 |
| 14:00 | 23:00 |
| 15:00 | 00:00 |
| 16:00 | 01:00 |
| 17:00 | 02:00 |
| 18:00 | 03:00 |
| 19:00 | 04:00 |
| 20:00 | 05:00 |
| 21:00 | 06:00 |
| 22:00 | 07:00 |
| 23:00 | 08:00 |
Greenwich Mean Time
Offset: GMT is 0 hours ahead Greenwich Mean Time (GMT) and is used in Europe
Countries using this time zone: 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 time zone is London in United Kingdom, with about 8.962 million people. Other major cities in this time zone include Abidjan, Bamako, Dakar, Kumasi.
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 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 - Universal Time Coordinated
- WT - Western Sahara Standard Time
- Z - Zulu Time Zone
Japan Standard Time
Offset: JST is 9 hours ahead Greenwich Mean Time (GMT) and is used in Asia
Countries using this time zone: Japan
Principal Cities: The largest city in the JST time zone is Tokyo in Japan, with about 9.733 million people. Other major cities in this time zone include Yokohama, Osaka shi, Nagoya shi, Sapporo.
Daylight Saving: Clocks in Japan Standard Time (JST) do not change for daylight saving time, so JST stays the same throughout the year. Other time zones may set clocks forward in summer and back in winter; see upcoming clock changes worldwide.
JST 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 east of the zero meridian.
- India - Military abbreviation for JST
- I - short form of 'India'
- Asia/Tokyo
- Japan
- AWDT - Australian Western Daylight Time
- CHOST - Choibalsan Summer Time
- I - India Time Zone
- IRKST - Irkutsk Summer Time
- JST - Japan Standard Time
- KST - Korea Standard Time
- PWT - Palau Time
- TLT - East Timor Time
- ULAST - Ulaanbaatar Summer Time
- WIT - Eastern Indonesian Time
- YAKT - Yakutsk Time