What is HST in ACST?
Australian Central Time is 19 hours 30 minutes ahead
Hawaii Standard Time is on UTC−10:00 and Australian Central Time is on UTC+9:30 right now. The gap changes during the year — see below.
- Time in Honolulu
- 4:56 pm
- Time in Adelaide
- 12:26 pm
- Difference
- +19:30 h
- Next clock change
- October 3, 2026
Convert a time
ACST — Australian Central Time
11:30 am
Wed, the next day
When the difference changes
Hawaii Standard Time and Australian Central 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, 2026Australian Central Time is 19 hours 30 minutes ahead
- October 3, 2026 – April 3, 2027Australian Central Time is 20 hours 30 minutes ahead
- April 3, 2027 – October 2, 2027Australian Central Time is 19 hours 30 minutes ahead
- October 2, 2027 – onwardsAustralian Central Time is 20 hours 30 minutes ahead
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
Hawaii Standard Time
Hawaii Standard Time stays on HST all year, so its offset from UTC never moves.
Australian Central Time
Clocks go forward one hour at 2am local time, becoming ACDT.
HST to ACST conversion table
Every hour of Tuesday, September 22, 2026, converted from Hawaii Standard Time to Australian Central Time. 19 of the 24 hours fall on a different calendar day in Adelaide, which is marked.
- 12:00 am HST
- 7:30 pm ACST
- 1:00 am HST
- 8:30 pm ACST
- 2:00 am HST
- 9:30 pm ACST
- 3:00 am HST
- 10:30 pm ACST
- 4:00 am HST
- 11:30 pm ACST
- 5:00 am HST
- 12:30 am ACST+1 day
- 6:00 am HST
- 1:30 am ACST+1 day
- 7:00 am HST
- 2:30 am ACST+1 day
- 8:00 am HST
- 3:30 am ACST+1 day
- 9:00 am HST
- 4:30 am ACST+1 day
- 10:00 am HST
- 5:30 am ACST+1 day
- 11:00 am HST
- 6:30 am ACST+1 day
- 12:00 pm HST
- 7:30 am ACST+1 day
- 1:00 pm HST
- 8:30 am ACST+1 day
- 2:00 pm HST
- 9:30 am ACST+1 day
- 3:00 pm HST
- 10:30 am ACST+1 day
- 4:00 pm HST
- 11:30 am ACST+1 day
- 5:00 pm HST
- 12:30 pm ACST+1 day
- 6:00 pm HST
- 1:30 pm ACST+1 day
- 7:00 pm HST
- 2:30 pm ACST+1 day
- 8:00 pm HST
- 3:30 pm ACST+1 day
- 9:00 pm HST
- 4:30 pm ACST+1 day
- 10:00 pm HST
- 5:30 pm ACST+1 day
- 11:00 pm HST
- 6:30 pm ACST+1 day
Scheduling between the two
Working hours overlap from 2:00 pm to 6:00 pm HST, which is 9:30 am to 1:30 pm ACST. Anything inside that window falls in the normal working day at both ends.
Hawaii Standard Time (HST) is used in all of Hawaii, which does not observe daylight saving
Australian Central Time (ACST) is used in South Australia and the Northern Territory, on a half-hour offset from the east coast