Current Time in ACST (Australian Central Standard Time)
About ACST
Used in South Australia, the Northern Territory, and the town of Broken Hill in New South Wales, Australia. It is notable for its half-hour offset from UTC. During daylight saving, South Australia switches to ACDT.
UTC Offset: +09:30
Current time shown is based on the representative IANA zone: Australia/Adelaide
Australian Central Standard Time (ACST)
Australian Central Standard Time (ACST) is the time zone observed in central Australia, including the states of South Australia and the Northern Territory, as well as the town of Broken Hill in western New South Wales. It is 9 hours and 30 minutes ahead of Coordinated Universal Time (UTC+09:30). The abbreviation ACST stands for Australian Central Standard Time, used during the non-daylight saving period.
Standard Offset and Daylight Saving
ACST is fixed at UTC+09:30 year-round in the Northern Territory and Broken Hill. However, South Australia observes daylight saving time (ACDT, Australian Central Daylight Time, UTC+10:30) from the first Sunday in October to the first Sunday in April. During this period, clocks in South Australia are set forward one hour, while the Northern Territory and Broken Hill remain on standard time.
Coverage: Regions, Countries, and Cities
ACST is used exclusively in Australia, covering the entire state of South Australia (including Adelaide, the capital), the Northern Territory (including Darwin and Alice Springs), and the town of Broken Hill in far western New South Wales. The IANA time zone identifiers grouped under ACST include Australia/Adelaide, Australia/Broken_Hill, Australia/Darwin, Australia/North, Australia/South, and Australia/Yancowinna.
How ACST Differs from Neighbouring Zones
ACST sits between Australian Western Standard Time (AWST, UTC+08:00) to the west and Australian Eastern Standard Time (AEST, UTC+10:00) to the east. The 90-minute offset from AWST and 30-minute offset from AEST are unique to central Australia. During South Australian daylight saving, ACDT (UTC+10:30) matches AEDT (Australian Eastern Daylight Time), but only for part of the year. This creates a complex patchwork: for example, when it is 12:00 noon in Adelaide (ACDT), it is 11:30 am in Darwin (ACST) and 12:30 pm in Sydney (AEDT).
Practical Business-Hours Guidance
When scheduling across Australian time zones, note that the 30-minute offset between ACST and AEST can cause confusion. For calls between Adelaide and Sydney, the best overlap is typically 10:00 am to 4:00 pm ACST (10:30 am to 4:30 pm AEST). During South Australian daylight saving, Adelaide aligns with Sydney (both UTC+10:30), making coordination easier. For international calls, ACST overlaps well with Asia (e.g., Singapore, UTC+08:00, is 1.5 hours behind) and partially with US West Coast (e.g., Los Angeles, UTC-08:00, is 17.5 hours behind during standard time). Avoid scheduling calls between 12:00 pm and 2:00 pm ACST if you need to reach both Perth (AWST) and Brisbane (AEST), as Perth is 1.5 hours behind and Brisbane is 0.5 hours ahead.
Key Facts About ACST
- ACST is one of only a few time zones worldwide that uses a half-hour offset from UTC.
- South Australia is the only state in the ACST zone that observes daylight saving time.
- Broken Hill, despite being in New South Wales (which primarily uses AEST), follows ACST due to its historical and economic ties to South Australia.
- The Northern Territory has never observed daylight saving time, maintaining ACST year-round.
- The IANA database lists multiple entries for ACST to account for historical and regional differences, but all currently share the same standard offset.
Frequently Asked Questions
What does ACST stand for?
ACST stands for Australian Central Standard Time. It is the standard time used in central Australia, with a UTC offset of +09:30.
Does the Northern Territory observe daylight saving time?
No, the Northern Territory does not observe daylight saving time. It remains on ACST (UTC+09:30) year-round.
Why does Broken Hill use ACST instead of AEST?
Broken Hill, located in western New South Wales, uses ACST because of its historical and economic ties to South Australia. The town is geographically closer to Adelaide and follows its time zone for convenience.
What is the time difference between ACST and AEST?
ACST is 30 minutes behind AEST. For example, when it is 12:00 pm in Adelaide (ACST), it is 12:30 pm in Sydney (AEST). During South Australian daylight saving, ACDT (UTC+10:30) matches AEDT.
When does South Australia switch to daylight saving time?
South Australia begins daylight saving at 2:00 am ACST on the first Sunday in October, moving clocks forward to 3:00 am ACDT. It ends at 2:00 am ACDT on the first Sunday in April, moving clocks back to 1:00 am ACST.
What are the major cities in the ACST zone?
Major cities include Adelaide (South Australia), Darwin and Alice Springs (Northern Territory), and the town of Broken Hill (New South Wales).