ACST to BST Converter

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ACST
Australian Central Standard Time
UTC+9:30
12am
3am
6am
9am
12pm
3pm
6pm
9pm
South Australia is on daylight saving time: ACDT (UTC+10:30) until Sun, Apr 4, 2027.

The Northern Territory stays on ACST (UTC+9:30).

GMT/BST
Greenwich Mean Time
UTC+0
9h 30m behind
12am
3am
6am
9am
12pm
3pm
6pm
9pm
The United Kingdom is on standard time: GMT (UTC+0) until Sun, Mar 28, 2027.
Keep BST (UTC+1)

Quick answers

Selected conversion

9:30 pm21:30 ACST (UTC+9:30), Oct 31, 2026 = 12:00 pm12:00 GMT (UTC+0), Oct 31, 2026

ACST is 9 hours and 30 minutes ahead of GMT.

ACST and BST examples

These examples always use ACST (UTC+9:30) and BST (UTC+1). They stay the same when you change the date or time above. The selected conversion may differ when daylight saving time applies.

ACST is 8 hours and 30 minutes ahead of BST.

How the time difference changes

For most of the year, ACST is 8 hours and 30 minutes ahead of BST. From Oct 25, 2026 to Mar 28, 2027, and from Oct 31, 2027 to Mar 26, 2028, ACST is 9 hours and 30 minutes ahead of GMT.

For most of the year, working hours of 9:00 am to 6:00 pm in ACST correspond to 12:30 am to 9:30 am in BST. At other times of the year, working hours of 9:00 am to 6:00 pm in ACST correspond to 11:30 pm (previous day) to 8:30 am in GMT.For most of the year, working hours of 09:00 to 18:00 in ACST correspond to 00:30 to 09:30 in BST. At other times of the year, working hours of 09:00 to 18:00 in ACST correspond to 23:30 (previous day) to 08:30 in GMT.

Compare ACST time with BST time, including current local time, UTC offsets, time difference, daylight saving changes, working hours, and shareable meeting times.

Time Difference

Australian Central Standard Time is 9 hours and 30 minutes ahead of Greenwich Mean Time.
9:30 pm21:30 in ACST is 12:00 pm12:00 in GMT

ACST to GMT call time
Best time for a conference call or a meeting is between 6pm-7pm18:00-19:00 in ACST which corresponds to 8:30am-9:30am08:30-09:30 in GMT. Their 9am–6pm09:00–18:00 working hours do not overlap; this is a suggested compromise.

9:30 pm21:30 Australian Central Standard Time (ACST). Offset UTC +9:30 hours
12:00 pm12:00 Greenwich Mean Time (GMT). Offset UTC 0:00 hours

9:30 pm21:30 ACST / 12:00 pm12:00 GMT

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.

Hourly time comparison
ACSTGMT
2:30pm previous day
3:30pm previous day
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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.

Map of the areas on Australian Central Standard Time (ACST)
ACST all year ACST part of the year

Today the lighter areas are on UTC+10:30 (ACDT).

Open the world time zone map© OpenStreetMap

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).

123456789101112End: 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.

123456789101112Start: 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

W3C/ISO-8601: International standard covering representation and exchange of dates and time-related data
  • +0930 - basic
  • +09:30 - extended
Email/RFC-2822: Internet Message Format Date Standard, typically used for timestamps in email headers
  • +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.
IANA/Olson: Reflects ACST time zone boundaries defined by political bodies, primarily intended for use with computer programs and operating systems
  • Australia/Adelaide
  • Australia/Broken_Hill
  • Australia/Darwin
  • Australia/North
  • Australia/South
  • Australia/Yancowinna

British Summer Time

Offset: BST is 1 hour ahead of Greenwich Mean Time (GMT).

Countries using this time zone: Guernsey, Isle of Man, Jersey, United Kingdom

Principal Cities: The largest city in the BST time zone is London in the United Kingdom, with about 8.962 million people. Other major cities in this time zone include Birmingham, Glasgow, Manchester, Sheffield.

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.

Current time in the United Kingdom: UK time now

Map of the areas on British Summer Time (BST)
BST part of the year

Today the shaded areas are on UTC+0 (GMT).

Open the world time zone map© OpenStreetMap

BST representations, usage and related time zones

W3C/ISO-8601: International standard covering representation and exchange of dates and time-related data
  • +01 - basic short
  • +0100 - basic
  • +01:00 - extended
Email/RFC-2822: Internet Message Format Date Standard, typically used for timestamps in email headers
  • +0100 - sign character (+) followed by a four digit time providing hours (01) and minutes (00) of the offset. Indicates an offset of one hour to the east of the zero meridian.
Military/NATO: Used by the U.S. military, Chinese military and others
  • Alpha - Military abbreviation for BST
  • A - short form of 'Alpha'
IANA/Olson: Reflects BST time zone boundaries defined by political bodies, primarily intended for use with computer programs and operating systems
  • Europe/Belfast
  • Europe/Guernsey
  • Europe/Isle_of_Man
  • Europe/Jersey
  • Europe/London
  • GB
  • GB-Eire
BST Abbreviation: Several time zones share BST abbreviation and it could refer to these time zones
  • British Summer Time - UTC +1
  • Bangladesh Standard Time - UTC +6
  • Bougainville Standard Time - UTC +11
Time zones with the GMT +1 offset:
  • BST - British Summer Time
  • CET - Central European Time
  • IST - Irish Standard Time
  • WEST - Western European Summer Time
  • A - Alpha Time Zone
  • CET - Central European Time
  • MEZ - Mitteleuropäische Zeit
  • WAT - West Africa Time
  • WST - Western Sahara Summer Time
  • BMT - Biel Mean Time