GMT to ACST Converter
The United Kingdom is on summer time: BST (UTC+1) until Sun, Oct 25.
Iceland and Ghana stay on GMT (UTC+0).
ACST is not used on this date
This converter keeps ACST at UTC+9:30. Adelaide uses ACDT (UTC+10:30) on this date. Open the ACDT converter, or choose Adelaide, Adelaide Hills, or Mount Gambier 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 = 9:30 pm21:30 ACST (UTC+9:30), Oct 18, 2026
GMT is 9 hours and 30 minutes behind ACST.
GMT and ACST examples
These examples always use GMT (UTC+0) and ACST (UTC+9:30). 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 and 30 minutes behind ACST.
How the time difference changes
GMT is 9 hours and 30 minutes behind ACST year-round.
Working hours of 9:00 am to 6:00 pm in GMT correspond to 6:30 pm to 3:30 am (next day) in ACST.Working hours of 09:00 to 18:00 in GMT correspond to 18:30 to 03:30 (next day) in ACST.
Compare GMT time with ACST 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 and 30 minutes behind Australian Central Standard Time.
12:00 pm12:00 in GMT is 9:30 pm21:30 in ACST
GMT to ACST call time
Best time for a conference call or a meeting is between 8:30am-9:30am08:30-09:30 in GMT which corresponds to 6pm-7pm18:00-19:00 in ACST. 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
9:30 pm21:30 Australian Central Standard Time (ACST). Offset UTC +9:30 hours
12:00 pm12:00 GMT / 9:30 pm21:30 ACST
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.
| GMT | ACST |
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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
Australian Central Standard Time
Offset: ACST is 9 hours and 30 minutes ahead of Greenwich Mean Time (GMT).
Countries using this time zone: Australia
Principal Cities: The largest city in the ACST time zone is Adelaide in Australia, with about 1.469 million people. Other major cities in this time zone include Darwin, Palmerston, Alice Springs, Mount Gambier.
Today the lighter areas are on UTC+10:30 (ACDT).
Daylight Saving: This is a standard time zone. During summer, some places set clocks forward one hour for daylight saving time and observe Australian Central Daylight Time (ACDT).
End: Australian Central Standard Time (ACST) ended on Sunday, October 4, 2026 at 2:00 am02:00 local time and clocks were set one hour forward to Sunday, October 4, 2026, 3:00 am03:00 local daylight time instead. Standard time ends annually on the first Sunday of October.
Start: Australian Central Standard Time (ACST) starts on Sunday, April 4, 2027 at 3:00 am03:00 local time and clocks are set one hour back to Sunday, April 4, 2027, 2:00 am02:00. Standard time starts annually on the first Sunday of April.
See Australia daylight saving time and upcoming clock changes worldwide.
ACST representations, usage and related time zones
- +0930 - basic
- +09:30 - extended
- +0930 - sign character (+) followed by a four digit time providing hours (09) and minutes (30) of the offset. Indicates an offset of nine hours and thirty minutes to the east of the zero meridian.
- Australia/Adelaide
- Australia/Broken_Hill
- Australia/Darwin
- Australia/North
- Australia/South
- Australia/Yancowinna