HST to AEDT
+21hHST
HSTSOURCEAEDT
AEDTGreen rows indicate typical business hours (9 AM - 5 PM)
HST and AEDT on the World Map
The map below highlights the HST (Hawaii Standard Time) and AEDT (Australian Eastern Daylight Time) timezone regions across the globe.
HST – Hawaii Standard Time
UTC-10:00Hawaii Standard Time (HST) is the time zone for the Hawaiian Islands, 10 hours behind UTC.
- •Hawaii does not observe daylight saving time.
- •HST is 5 hours behind EST in winter and 6 hours behind EDT in summer.
- •Hawaii is one of only two US states that don't observe DST (the other is Arizona).
AEDT – Australian Eastern Daylight Time
UTC+11:00Australian Eastern Daylight Time (AEDT, UTC+11:00) is the daylight saving period in south-eastern Australia, from October to April.
- •AEDT runs from the first Sunday in October to the first Sunday in April.
- •AEDT is one hour ahead of Australian Eastern Standard Time (AEST).
- •Queensland does not observe daylight saving, so Brisbane stays on AEST.
- •During AEDT, Sydney is 16 hours ahead of New York and 11 hours ahead of UTC.
Everything You Need to Know About HST and AEDT Time
HST runs on Hawaii Standard Time (HST) at UTC-10:00. AEDT runs on Australian Eastern Daylight Time (AEDT) at UTC+11:00. That puts HST 21 hours ahead of AEDT — a difference of +21h at the current offsets.
In practice, when it is 9:00 AM in HST it is 6:00 AM in AEDT on the next day. Midnight in HST is 9:00 PM in AEDT. Neither zone observes daylight saving time, so the offset between them stays constant all year.
HST to AEDT time conversion table
| HST (HST) | AEDT (AEDT) | Day |
|---|---|---|
| 12:00 AM | 9:00 PM | same day |
| 6:00 AM | 3:00 AM | next day |
| 7:00 AM | 4:00 AM | next day |
| 8:00 AM | 5:00 AM | next day |
| 9:00 AM | 6:00 AM | next day |
| 12:00 PM | 9:00 AM | next day |
| 3:00 PM | 12:00 PM | next day |
| 5:00 PM | 2:00 PM | next day |
| 6:00 PM | 3:00 PM | next day |
| 9:00 PM | 6:00 PM | next day |
Why people convert HST to AEDT time
- Scheduling a call from HST to AEDT: a 10:00 AM start in HST lands at 7:00 AM in AEDT the next day, so you can confirm the slot without doing the arithmetic yourself.
- Handling a +21h gap: HST and AEDT have no overlap inside a normal 9-to-5 day, so real-time meetings need an early-morning or late-evening slot on one side. 9:00 AM in AEDT is 6:00 AM in HST.
- Keeping family and friends in sync: knowing that 8:00 PM in HST is 5:00 PM in AEDT makes it easy to avoid calling at 3 AM.
- Always state the zone abbreviation, not just the hour. "3:00 PM HST" is unambiguous; "3 PM" across a +21h gap is not.
- With a +21h gap there is no shared 9-to-5 window, so alternate the early start: one week HST takes the early slot, the next week AEDT does.
About HST (Hawaii Standard Time)
Hawaii Standard Time (HST) is used in the state of Hawaii and does not observe daylight saving time. This makes HST one of the most consistent time zones in the US. The Hawaiian Islands are among the last places on Earth to see a new calendar day.
About AEDT (Australian Eastern Daylight Time)
Australian Eastern Daylight Time (AEDT) is the daylight saving period in south-eastern Australia, one hour ahead of Australian Eastern Standard Time (AEST, UTC+10:00). Because Australia is in the southern hemisphere, AEDT runs through the summer — from the first Sunday in October to the first Sunday in April — which is almost exactly the reverse of the European and North American schedules. New South Wales, Victoria, Tasmania and the Australian Capital Territory observe it; Queensland and the Northern Territory do not, so Brisbane stays on AEST year round while Sydney moves to AEDT. During AEDT, Sydney is 11 hours ahead of UTC and 16 hours ahead of New York.
Best time to call between HST and AEDT
With a +21h offset there is no overlap inside a normal 9 AM – 5 PM day. AEDT opens at 9:00 AM AEDT, which is 6:00 AM in HST, so real-time calls need an early-morning or late-evening slot on one side.
Business hours overlap
HST and AEDT have no shared working hours because of the +21h gap. Teams need to alternate early starts or rely on asynchronous handovers.
HST is 21 hours ahead of AEDT (HST UTC-10:00 → AEDT UTC+11:00). There is no shared 9-to-5 window, so plan around an early or late slot. Remember to re-check around daylight-saving transitions.
🕐 Daylight Saving Time Info
HST
Does not observe DST
AEDT
❄ Currently in Standard Time
Standard: UTC+10:00 · DST: UTC+11:00
Clocks spring forward on Sat, Oct 3, 2026
Learn More About Time
Dive deeper into the fascinating world of timekeeping, time zones, and how they shape our global society:
Frequently Asked Questions
What is the time difference between HST and AEDT?
HST (HST, UTC-10:00) is 21 hours ahead of AEDT (AEDT, UTC+11:00). The gap is currently +21h.
How do I convert HST time to AEDT time?
Add +21h to HST local time. For example, 9:00 AM in HST is 6:00 AM in AEDT (next day).
What time is it in AEDT right now?
AEDT uses AEDT at UTC+11:00. Use the live converter at the top of this page — it updates in real time and already accounts for the +21h offset from HST.
What is the best time to call AEDT from HST?
There is no shared working-hours window because of the +21h gap. The closest option is 1:00 PM in HST, which is 10:00 AM in AEDT.
Which is ahead, HST or AEDT?
HST is 21 hours ahead of AEDT. When it is 12:00 PM in HST it is 9:00 AM in AEDT.
Does daylight saving time affect the HST–AEDT difference?
Neither zone observes daylight saving time, so the +21h offset between HST and AEDT is fixed all year.
Which other cities share HST's time zone?
HST also covers Honolulu, Hilo, Kailua, Pearl City, Kapolei.
Which countries use HST, HST's zone?
HST is used in United States (Hawaii).
Is there a day difference between HST and AEDT?
Sometimes. The +21h gap is large enough that 8:00 PM or later in HST already falls on the next day in AEDT.
What is the time difference between HST and AEDT?
AEDT is +21h from HST.
What timezone is HST in?
HST operates on its local timezone.
What timezone is AEDT in?
AEDT operates on its local timezone.
Which countries use HST (Hawaii Standard Time)?
HST is used in United States (Hawaii).
Does HST observe daylight saving time?
No, HST does not observe daylight saving time and remains at UTC-10:00 year-round.
What are some interesting facts about HST?
Hawaii does not observe daylight saving time. HST is 5 hours behind EST in winter and 6 hours behind EDT in summer.
Which cities are in the AEDT timezone?
Major cities in the AEDT timezone include Sydney, Melbourne, Canberra, Hobart, Newcastle.
What is the UTC offset for AEDT?
Australian Eastern Daylight Time (AEDT) is at UTC+11:00. During daylight saving time, it shifts to AEDT.
What should I know about the AEDT timezone?
AEDT runs from the first Sunday in October to the first Sunday in April. AEDT is one hour ahead of Australian Eastern Standard Time (AEST).
When is it midnight in HST, what time is it in AEDT?
When it is 12:00 AM (midnight) in HST (HST), it is +21h later in AEDT (AEDT).
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See every conversion from HST →·See every conversion from AEDT →