HST to ACST: HST is 19 hours 30 minutes behind ACST
Hawaii Standard Time is 19 hours 30 minutes behind Australian Central Time right now. It is 3:04 pm HST in Hawaii and 10:34 am ACST in Australian Central, which is already the next day there.
Convert a specific time from HST to ACST
Pick any time and date to convert it both ways. The conversion runs in your browser against the real zone rules, so a date inside a daylight saving period gets that period's offset rather than today's.
What is the time difference between HST and ACST?
Australian Central Time is 19 hours 30 minutes ahead of Hawaii Standard Time. To go from HST to ACST you add 19 hours 30 minutes. That gap is not fixed. Across 2026 the distance between these two zones takes 2 different values, from 19 hours 30 minutes to 20 hours 30 minutes, because Australian Central moves its clocks and Hawaii does not. This page recomputes it rather than assuming.
HST to ACST conversion table
Every hour of Thursday, September 24, 2026 in Hawaii, with the matching reading in Australian Central. 19 of the 24 hours land on a different calendar date in Australian Central, which is the part people get wrong when they schedule across this pair.
| HST | HST 24h | ACST | ACST 24h | Date |
|---|---|---|---|---|
| 12:00 am | 00:00 | 7:30 pm | 19:30 | same day |
| 1:00 am | 01:00 | 8:30 pm | 20:30 | same day |
| 2:00 am | 02:00 | 9:30 pm | 21:30 | same day |
| 3:00 am | 03:00 | 10:30 pm | 22:30 | same day |
| 4:00 am | 04:00 | 11:30 pm | 23:30 | same day |
| 5:00 am | 05:00 | 12:30 am | 00:30 | the next day |
| 6:00 am | 06:00 | 1:30 am | 01:30 | the next day |
| 7:00 am | 07:00 | 2:30 am | 02:30 | the next day |
| 8:00 am | 08:00 | 3:30 am | 03:30 | the next day |
| 9:00 am | 09:00 | 4:30 am | 04:30 | the next day |
| 10:00 am | 10:00 | 5:30 am | 05:30 | the next day |
| 11:00 am | 11:00 | 6:30 am | 06:30 | the next day |
| 12:00 pm | 12:00 | 7:30 am | 07:30 | the next day |
| 1:00 pm | 13:00 | 8:30 am | 08:30 | the next day |
| 2:00 pm | 14:00 | 9:30 am | 09:30 | the next day |
| 3:00 pm | 15:00 | 10:30 am | 10:30 | the next day |
| 4:00 pm | 16:00 | 11:30 am | 11:30 | the next day |
| 5:00 pm | 17:00 | 12:30 pm | 12:30 | the next day |
| 6:00 pm | 18:00 | 1:30 pm | 13:30 | the next day |
| 7:00 pm | 19:00 | 2:30 pm | 14:30 | the next day |
| 8:00 pm | 20:00 | 3:30 pm | 15:30 | the next day |
| 9:00 pm | 21:00 | 4:30 pm | 16:30 | the next day |
| 10:00 pm | 22:00 | 5:30 pm | 17:30 | the next day |
| 11:00 pm | 23:00 | 6:30 pm | 18:30 | the next day |
What are the best hours to schedule a call between HST and ACST?
No hour of the standard 9:00 am to 5:00 pm working day falls inside working hours on both sides. Hawaii and Australian Central are 19 hours 30 minutes apart, which is too far for an overlap, so somebody has to take a call outside their own working day. The least painful options are below, ranked by how close both sides sit to the middle of the afternoon.
| HST | ACST | Working hours | Note |
|---|---|---|---|
| 1:00 pm | 8:30 am the next day | HST only | afternoon in Hawaii, mid morning in Australian Central |
| 2:00 pm | 9:30 am the next day | both sides | afternoon in Hawaii, mid morning in Australian Central |
| 3:00 pm | 10:30 am the next day | both sides | afternoon in Hawaii, mid morning in Australian Central |
Does daylight saving change HST to ACST?
Hawaii Standard Time does not move its clocks at all, so its UTC-10 offset holds every day of the year.
Australian Central Time is currently on ACST and changes next on Sunday, October 4, 2026, when the clock jumps forward from 1:59 am to 3:00 am and the offset moves from UTC+9:30 to UTC+10:30.
Because the two sides do not move together, the answer to this conversion changes during the year. For part of the year the gap is 19 hours 30 minutes and for the rest it is 20 hours 30 minutes. The table above is built for today, not for an average day.
Is HST ahead of or behind ACST?
HST is behind ACST by 19 hours 30 minutes: when it is 12:00 pm in Hawaii, it is 7:30 am the next day in Australian Central. One wrinkle worth knowing: ACST and ACDT are two names for the same zone, not two zones. Australian Central Time reads ACST in winter and ACDT in summer. When somebody types "hst to acst" they nearly always mean the zone rather than the literal winter offset, so this page resolves HST to Pacific/Honolulu and ACST to Australia/Adelaide and applies whichever offset is genuinely in force on the day.
Hawaii Standard Time covers Hawaii, which has never moved its clocks. Australian Central Time covers Adelaide and South Australia, on a half hour offset that also shifts for summer. The identifiers behind them are Pacific/Honolulu and Australia/Adelaide, which is what any calendar or scheduling system should be storing rather than a fixed number of hours.
Questions
- What is HST in ACST?
- HST is 19 hours 30 minutes behind ACST. 9:00 am HST is 4:30 am the next day ACST.
- How many hours ahead is ACST of HST?
- ACST is 19 hours 30 minutes ahead of HST. That varies across the year, between 19 hours 30 minutes and 20 hours 30 minutes.
- What time is it in Australian Central right now?
- 10:34 am ACST on Friday, September 25, 2026.
- When can Hawaii and Australian Central meet during working hours?
- There is no shared working hour. The closest fit is 1:00 pm HST, which is 8:30 am ACST.
- Does this account for daylight saving?
- Yes. Every reading is computed from the IANA database for the actual date, so HST and ACST are the abbreviations genuinely in force today rather than a fixed assumption.
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