HST to AST
+6hHST
HSTSOURCEAST
ASTGreen rows indicate typical business hours (9 AM - 5 PM)
HST and AST on the World Map
The map below highlights the HST (Hawaii Standard Time) and AST (Atlantic Standard 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).
AST – Atlantic Standard Time
UTC-04:00Atlantic Standard Time (AST) is the time zone for the Canadian Atlantic provinces and the Caribbean, 4 hours behind UTC.
- •Puerto Rico uses AST year-round and does not observe DST.
- •AST is 1 hour ahead of EST.
- •Halifax, the capital of Nova Scotia, is the largest city in AST Canada.
Everything You Need to Know About HST and AST Time
HST runs on Hawaii Standard Time (HST) at UTC-10:00. AST runs on Atlantic Standard Time (AST) at UTC-04:00. That puts HST 6 hours ahead of AST — a difference of +6h at the current offsets.
In practice, when it is 9:00 AM in HST it is 3:00 PM in AST. Midnight in HST is 6:00 AM in AST. Neither zone observes daylight saving time, so the offset between them stays constant all year.
HST to AST time conversion table
| HST (HST) | AST (AST) | Day |
|---|---|---|
| 12:00 AM | 6:00 AM | same day |
| 6:00 AM | 12:00 PM | same day |
| 7:00 AM | 1:00 PM | same day |
| 8:00 AM | 2:00 PM | same day |
| 9:00 AM | 3:00 PM | same day |
| 12:00 PM | 6:00 PM | same day |
| 3:00 PM | 9:00 PM | same day |
| 5:00 PM | 11:00 PM | same day |
| 6:00 PM | 12:00 AM | next day |
| 9:00 PM | 3:00 AM | next day |
Why people convert HST to AST time
- Scheduling a call from HST to AST: a 10:00 AM start in HST lands at 4:00 PM in AST, so you can confirm the slot without doing the arithmetic yourself.
- Finding shared working hours: both HST and AST are inside the 9-to-5 working day between 9:00 AM and 11:00 AM HST time (3:00 PM–5:00 PM AST). That is roughly 2 hours of usable overlap.
- Keeping family and friends in sync: knowing that 8:00 PM in HST is 2:00 AM in AST 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 +6h gap is not.
- Block 9:00 AM–11:00 AM HST as the recurring meeting window if you work primarily from HST and need AST colleagues present.
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 AST (Atlantic Standard Time)
Atlantic Standard Time (AST) covers Canada's Atlantic provinces (Nova Scotia, New Brunswick, Prince Edward Island, and most of Labrador), as well as several Caribbean nations. Puerto Rico and the US Virgin Islands use AST year-round without daylight saving time. The Canadian provinces switch to Atlantic Daylight Time (ADT) in summer.
Best time to call between HST and AST
Both HST and AST sit inside the 9 AM – 5 PM working day between 9:00 AM–11:00 AM HST, which is 3:00 PM–5:00 PM AST. That gives roughly 2 hours of shared time — the safest window for a live call or meeting.
Business hours overlap
HST and AST overlap for about 2 hours during the working day — enough for meetings if you avoid the edges of the window.
HST is 6 hours ahead of AST (HST UTC-10:00 → AST UTC-04:00). The shared working window is 9:00 AM–11:00 AM HST. Remember to re-check around daylight-saving transitions.
🕐 Daylight Saving Time Info
HST
Does not observe DST
AST
☀ Currently in DST
Standard: UTC-04:00 · DST: UTC-03:00
Clocks fall back on Sun, Nov 1, 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 AST?
HST (HST, UTC-10:00) is 6 hours ahead of AST (AST, UTC-04:00). The gap is currently +6h.
How do I convert HST time to AST time?
Add +6h to HST local time. For example, 9:00 AM in HST is 3:00 PM in AST.
What time is it in AST right now?
AST uses AST at UTC-04:00. Use the live converter at the top of this page — it updates in real time and already accounts for the +6h offset from HST.
What is the best time to call AST from HST?
Call between 9:00 AM and 11:00 AM HST — that maps to 3:00 PM–5:00 PM AST and keeps both parties inside the working day.
Which is ahead, HST or AST?
HST is 6 hours ahead of AST. When it is 12:00 PM in HST it is 6:00 PM in AST.
Does daylight saving time affect the HST–AST difference?
Neither zone observes daylight saving time, so the +6h offset between HST and AST 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 AST?
Not normally. The +6h gap only pushes the date over for late-evening times.
What is the time difference between HST and AST?
AST is +6h from HST.
What timezone is HST in?
HST operates on its local timezone.
What timezone is AST in?
AST 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 AST timezone?
Major cities in the AST timezone include Halifax, San Juan, Santo Domingo, Caracas, La Paz, Fredericton, Charlottetown.
What is the UTC offset for AST?
Atlantic Standard Time (AST) is at UTC-04:00. During daylight saving time, it shifts to ADT.
What should I know about the AST timezone?
Puerto Rico uses AST year-round and does not observe DST. AST is 1 hour ahead of EST.
When is it midnight in HST, what time is it in AST?
When it is 12:00 AM (midnight) in HST (HST), it is +6h later in AST (AST).
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See every conversion from HST →·See every conversion from AST →