Skip to content
DateAlmanac

What is HST in ACST?

Australian Central Time is 20 hours 30 minutes ahead

Hawaii Standard Time is on UTC−10:00 and Australian Central Time is on UTC+10:30 right now. Australian Central Time is on daylight saving, so its clocks read ACDT. The gap changes during the year — see below.

Convert a time

ACDT — Australian Central Time

6:30 pm

ACDT, Sat, the next day

Time in Honolulu
10:29:50 PM
Time in Adelaide
6:59:50 PM
Difference
+20:30 h
Next clock change
April 4, 2027

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:

  1. Now – April 3, 2027Australian Central Time is 20 hours 30 minutes ahead
  2. April 3, 2027 – October 2, 2027Australian Central Time is 19 hours 30 minutes ahead
  3. October 2, 2027 – onwardsAustralian Central Time is 20 hours 30 minutes ahead

Periods shorter than a day are not listed. Each zone changes at its own local time, so on a date when both move there are a few hours when the gap is briefly something else.

Daylight saving

Hawaii Standard Time

No clock changes

Hawaii Standard Time stays on HST all year, so its offset from UTC never moves.

Australian Central Time

Sunday, April 4, 2027

Clocks go back one hour — 3:00 am becomes 2:00 am local time, and the zone is on ACST after that.

HST to ACST conversion table

Every hour of Friday, November 6, 2026, converted from Hawaii Standard Time to Australian Central Time. 20 of the 24 hours fall on a different calendar day in Adelaide, which is marked.

12:00 am HST
8:30 pm ACDT
1:00 am HST
9:30 pm ACDT
2:00 am HST
10:30 pm ACDT
3:00 am HST
11:30 pm ACDT
4:00 am HST
12:30 am ACDT+1 day
5:00 am HST
1:30 am ACDT+1 day
6:00 am HST
2:30 am ACDT+1 day
7:00 am HST
3:30 am ACDT+1 day
8:00 am HST
4:30 am ACDT+1 day
9:00 am HST
5:30 am ACDT+1 day
10:00 am HST
6:30 am ACDT+1 day
11:00 am HST
7:30 am ACDT+1 day
12:00 pm HST
8:30 am ACDT+1 day
1:00 pm HST
9:30 am ACDT+1 day
2:00 pm HST
10:30 am ACDT+1 day
3:00 pm HST
11:30 am ACDT+1 day
4:00 pm HST
12:30 pm ACDT+1 day
5:00 pm HST
1:30 pm ACDT+1 day
6:00 pm HST
2:30 pm ACDT+1 day
7:00 pm HST
3:30 pm ACDT+1 day
8:00 pm HST
4:30 pm ACDT+1 day
9:00 pm HST
5:30 pm ACDT+1 day
10:00 pm HST
6:30 pm ACDT+1 day
11:00 pm HST
7:30 pm ACDT+1 day

Scheduling between the two

Working hours overlap from 1:00 pm to 6:00 pm HST, which is 9:30 am to 2:30 pm ACDT. 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 (ACDT) is used in South Australia and the Northern Territory, on a half-hour offset from the east coast

Other conversions