GMT to CAST Converter
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The selected date and time will appear here when the converter loads.
GMT and CAST examples
These examples always use GMT (UTC+0) and CAST (UTC+8). They stay the same when you change the date or time above. The selected conversion may differ when daylight saving time applies.
GMT is 8 hours behind CAST.
How the time difference changes
GMT is 8 hours behind CAST year-round.
Working hours of 9:00 am to 5:00 pm in GMT correspond to 5:00 pm to 1:00 am (next day) in CAST.
Compare GMT time with CAST time, including current local time, UTC offsets, time difference, daylight saving changes, working hours, and shareable meeting times.
Time Difference
Greenwich Mean Time is 8 hours behind Casey Time
12:00 pm12:00 in GMT is 8:00 pm20:00 in CAST
GMT to CAST call time
Best time for a conference call or a meeting is between 8:30am-9:30am in GMT which corresponds to 4:30pm-5:30pm in CAST
12:00 pm12:00 Greenwich Mean Time (GMT). Offset UTC 0:00 hours
8:00 pm20:00 Casey Time (CAST). Offset UTC +8:00 hours
12:00 pm12:00 GMT / 8:00 pm20:00 CAST
| GMT | CAST |
|---|---|
| 12am (midnight) | 8am |
| 1am | 9am |
| 2am | 10am |
| 3am | 11am |
| 4am | 12pm (noon) |
| 5am | 1pm |
| 6am | 2pm |
| 7am | 3pm |
| 8am | 4pm |
| 9am | 5pm |
| 10am | 6pm |
| 11am | 7pm |
| 12pm (noon) | 8pm |
| 1pm | 9pm |
| 2pm | 10pm |
| 3pm | 11pm |
| 4pm | 12am (midnight) |
| 5pm | 1am |
| 6pm | 2am |
| 7pm | 3am |
| 8pm | 4am |
| 9pm | 5am |
| 10pm | 6am |
| 11pm | 7am |
| 00:00 | 08:00 |
| 01:00 | 09:00 |
| 02:00 | 10:00 |
| 03:00 | 11:00 |
| 04:00 | 12:00 |
| 05:00 | 13:00 |
| 06:00 | 14:00 |
| 07:00 | 15:00 |
| 08:00 | 16:00 |
| 09:00 | 17:00 |
| 10:00 | 18:00 |
| 11:00 | 19:00 |
| 12:00 | 20:00 |
| 13:00 | 21:00 |
| 14:00 | 22:00 |
| 15:00 | 23:00 |
| 16:00 | 00:00 |
| 17:00 | 01:00 |
| 18:00 | 02:00 |
| 19:00 | 03:00 |
| 20:00 | 04:00 |
| 21:00 | 05:00 |
| 22:00 | 06:00 |
| 23:00 | 07:00 |
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
Casey Time
Offset: CAST is 8 hours ahead Greenwich Mean Time (GMT) and is used in Antarctica
Countries using this time zone: Antarctica
Daylight Saving: Clocks in Casey Time (CAST) do not change for daylight saving time, so CAST stays the same throughout the year. Other time zones may set clocks forward in summer and back in winter.
CAST representations, usage and related time zones
- +08 - basic short
- +0800 - basic
- +08:00 - extended
- +0800 - sign character (+) followed by a four digit time providing hours (08) and minutes (00) of the offset. Indicates an offset of eight hours to the east of the zero meridian.
- Hotel - Military abbreviation for CAST
- H - short form of 'Hotel'
- ACT - ASEAN Common Time
- AWST - Australian Western Standard Time
- BNT - Brunei Darussalam Time
- CAST - Casey Time
- CHOT - Choibalsan Time
- CST - China Standard Time
- H - Hotel Time Zone
- HKT - Hong Kong Time
- HOVST - Hovd Summer Time
- IRKT - Irkutsk Time
- KRAST - Krasnoyarsk Summer Time
- MYT - Malaysia Time
- PHT - Philippine Time
- SGT - Singapore Time
- ULAT - Ulaanbaatar Time
- WITA - Central Indonesian Time