What is ACST in HST?
Hawaii Standard Time is 19 hours 30 minutes behind
Australian Central Time is on UTC+9:30 and Hawaii Standard Time is on UTC−10:00 right now. The gap changes during the year — see below.
- Time in Adelaide
- 11:44 am
- Time in Honolulu
- 4:14 pm
- Difference
- −19:30 h
- Next clock change
- October 3, 2026
Convert a time
HST — Hawaii Standard Time
3:30 pm
Tue, the previous day
When the difference changes
Australian Central Time and Hawaii Standard Time do not change their clocks on the same dates, so the gap between them is not the same all year. Most converters show only today’s figure. These are the periods ahead:
- Now – October 3, 2026Hawaii Standard Time is 19 hours 30 minutes behind
- October 3, 2026 – April 3, 2027Hawaii Standard Time is 20 hours 30 minutes behind
- April 3, 2027 – October 2, 2027Hawaii Standard Time is 19 hours 30 minutes behind
- October 2, 2027 – onwardsHawaii Standard Time is 20 hours 30 minutes behind
Periods shorter than a day are not listed: both zones change at 2am in their own local time, so there are a few hours on each transition date when the gap is briefly something else.
Daylight saving
Australian Central Time
Clocks go forward one hour at 2am local time, becoming ACDT.
Hawaii Standard Time
Hawaii Standard Time stays on HST all year, so its offset from UTC never moves.
ACST to HST conversion table
Every hour of Wednesday, September 23, 2026, converted from Australian Central Time to Hawaii Standard Time. 20 of the 24 hours fall on a different calendar day in Honolulu, which is marked.
- 12:00 am ACST
- 4:30 am HST−1 day
- 1:00 am ACST
- 5:30 am HST−1 day
- 2:00 am ACST
- 6:30 am HST−1 day
- 3:00 am ACST
- 7:30 am HST−1 day
- 4:00 am ACST
- 8:30 am HST−1 day
- 5:00 am ACST
- 9:30 am HST−1 day
- 6:00 am ACST
- 10:30 am HST−1 day
- 7:00 am ACST
- 11:30 am HST−1 day
- 8:00 am ACST
- 12:30 pm HST−1 day
- 9:00 am ACST
- 1:30 pm HST−1 day
- 10:00 am ACST
- 2:30 pm HST−1 day
- 11:00 am ACST
- 3:30 pm HST−1 day
- 12:00 pm ACST
- 4:30 pm HST−1 day
- 1:00 pm ACST
- 5:30 pm HST−1 day
- 2:00 pm ACST
- 6:30 pm HST−1 day
- 3:00 pm ACST
- 7:30 pm HST−1 day
- 4:00 pm ACST
- 8:30 pm HST−1 day
- 5:00 pm ACST
- 9:30 pm HST−1 day
- 6:00 pm ACST
- 10:30 pm HST−1 day
- 7:00 pm ACST
- 11:30 pm HST−1 day
- 8:00 pm ACST
- 12:30 am HST
- 9:00 pm ACST
- 1:30 am HST
- 10:00 pm ACST
- 2:30 am HST
- 11:00 pm ACST
- 3:30 am HST
Scheduling between the two
Working hours overlap from 9:00 am to 2:00 pm ACST, which is 1:30 pm to 6:30 pm HST. Anything inside that window falls in the normal working day at both ends.
Australian Central Time (ACST) is used in South Australia and the Northern Territory, on a half-hour offset from the east coast
Hawaii Standard Time (HST) is used in all of Hawaii, which does not observe daylight saving