HST to AST Converter
Convert time between Hawaii Standard Time (HST) and Atlantic Standard Time (AST)
Hawaii Standard Time (HST)
Atlantic Standard Time (AST)
Time Difference
Atlantic Standard Time (AST) is 0 hours ahead of Hawaii Standard Time (HST)
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Select Time
Quick Reference
| HST | AST |
|---|---|
| 16:00 | 22:00 |
| 18:00 | 00:00 |
| 20:00 | 02:00 |
| 22:00 | 04:00 |
| 00:00 | 06:00 |
| 02:00 | 08:00 |
| 04:00 | 10:00 |
| 06:00 | 12:00 |
| 08:00 | 14:00 |
| 10:00 | 16:00 |
| 12:00 | 18:00 |
| 14:00 | 20:00 |
Top 10 Most Common Time Zones
| Abbreviation | Full Name | UTC Offset | Typical Use |
|---|---|---|---|
| UTC | Coordinated Universal Time | UTC ±0 | Global reference standard (servers, logs, APIs) |
| EST / EDT | Eastern (US) Time | UTC −5 / −4 | New York, Toronto — North American business hub |
| CST / CDT | Central (US) Time | UTC −6 / −5 | Chicago, Dallas — US central business region |
| PST / PDT | Pacific (US) Time | UTC −8 / −7 | San Francisco, Los Angeles — tech industry standard |
| GMT / BST | Greenwich Mean / British Summer Time | UTC 0 / +1 | UK, used globally as a reference with UTC |
| CET / CEST | Central European (Summer) Time | UTC +1 / +2 | Paris, Berlin, Amsterdam — EU business core |
| IST | India Standard Time | UTC +5:30 | India — major IT & outsourcing region |
| CST | China Standard Time | UTC +8 | Beijing, Shanghai — East Asia business hub |
| JST | Japan Standard Time | UTC +9 | Tokyo — finance & tech hub |
| AEST / AEDT | Australian Eastern (Daylight) Time | UTC +10 / +11 | Sydney, Melbourne — APAC regional business |
Why Time Zone Abbreviations Are Ambiguous
Unlike standardized identifiers (like America/New_York or Europe/London from the IANA tz database), abbreviations such as "CST" or "IST" are not globally unique. They can refer to different time zones depending on context — country, region, or even time of year (due to daylight saving time).
Common Ambiguous Time Zone Abbreviations
| Abbrev. | Common Meaning(s) | UTC Offset | Region(s) |
|---|---|---|---|
| CST | Central Standard Time / China Standard Time / Cuba Standard Time | UTC−6 / UTC+8 / UTC−5 | North America, China, Cuba |
| IST | Indian Standard Time / Irish Standard Time / Israel Standard Time | UTC+5:30 / UTC+1 / UTC+2 | India, Ireland, Israel |
| AST | Atlantic Standard Time / Arabia Standard Time | UTC−4 / UTC+3 | Caribbean, Canada, Middle East |
| PST | Pacific Standard Time / Philippine Standard Time | UTC−8 / UTC+8 | North America, Philippines |
| EST | Eastern Standard Time (North America / Australia) | UTC−5 / UTC+10 | North America, Australia |
✅ Best Practice
To avoid ambiguity, always:
- Use IANA tz identifiers — e.g.,
America/New_Yorkinstead of "EST" - Specify UTC offset explicitly — e.g.,
UTC−5when abbreviations must be used - Include the full timezone name — e.g., "Eastern Standard Time (EST)" with UTC offset
Related Time Zone Conversions
About HST to AST Time Conversion
Converting time between Hawaii Standard Time (HST) and Atlantic Standard Time (AST) is important for coordinating between Hawaii and the Atlantic region during standard time. HST is UTC-10 year-round, while AST is UTC-4 (observed November to March). AST is 6 hours ahead of HST during the winter season.
This conversion is vital for businesses coordinating between Atlantic Canada and Hawaii. Whether you're scheduling meetings between Atlantic Canadian cities and Honolulu headquarters, managing distributed teams across the Atlantic and Pacific, or planning travel between Atlantic Canada and Hawaiian offices, our accurate IANA-based converter ensures precise timezone calculations. The 6-hour difference during AST season requires careful attention to scheduling to find overlapping business hours between these distant regions.
Common Use Cases for HST to AST Conversion
Business & Work
- Scheduling calls between Hawaii and Atlantic Canada during standard time
- Coordinating between Atlantic Canada and Hawaii headquarters
- Managing business operations across Atlantic and Hawaiian regions
- Planning conference calls between Atlantic Canada and Hawaii teams
Personal & Travel
- Scheduling video calls with family and friends in Atlantic Canada
- Planning travel between Hawaii and Atlantic Canadian destinations
- Coordinating vacation time across regions during winter months
- Arranging online meetings with Atlantic Canada-based colleagues
Time Zone Information
Hawaii Standard Time (HST)
- UTC Offset: UTC-10
- IANA Timezone: Pacific/Honolulu
- Daylight Saving: No daylight saving time observed
- Major Cities: Honolulu, Hilo, Maui, Kauai, Big Island
- Coverage: State of Hawaii
Atlantic Standard Time (AST)
- UTC Offset: UTC-4 (UTC-3 during ADT)
- IANA Timezone: America/Halifax
- Daylight Saving: First Sunday in November to Second Sunday in March
- Major Cities: Halifax, Saint John, Fredericton, Moncton, St. John's
- Coverage: Atlantic Canada and US Atlantic territories
Quick Reference: HST to AST
Remember: AST is 6 hours ahead of HST during standard time (November-March). When daylight saving begins and AST becomes ADT (UTC-3), the difference increases to 7 hours. Hawaii does not observe daylight saving time, so HST remains constant year-round.
Frequently Asked Questions
What is the time difference between HST and AST?
Hawaii Standard Time (HST) is UTC-10, while Atlantic Standard Time (AST) is UTC-4. AST is 6 hours ahead of HST. This means when it's 8:00 AM in HST, it's 2:00 PM the same day in AST.
Does Hawaii observe daylight saving time?
No, Hawaii does not observe daylight saving time. Hawaii Standard Time (HST) remains UTC-10 year-round. However, the Atlantic region observes daylight saving time, transitioning from AST (UTC-4) to ADT (UTC-3). This means the time difference varies between 6 hours (when AST is active, November-March) and 7 hours (when ADT is active, March-November).
How does HST to AST differ from HST to EDT?
AST (Atlantic Standard Time) is 2 hours ahead of EDT (Eastern Daylight Time). When AST is active (November-March), the difference between HST and AST is 6 hours. When ADT is active (March-November), the difference becomes 7 hours. AST/ADT is used in the Atlantic region including parts of Canada and Caribbean territories.
What major regions are in HST and AST timezones?
HST covers Hawaii cities including Honolulu, Hilo, Maui, Kauai, and the Big Island. AST covers Atlantic region cities and territories including Halifax (Nova Scotia), Saint John (New Brunswick), Puerto Rico, and the US Virgin Islands. These regions represent Hawaii and the Atlantic coast/Caribbean during standard time (November-March).
How do I convert HST to AST manually?
To convert from HST to AST, add 6 hours to the HST time. For example, if it's 9:00 AM HST, it would be 3:00 PM AST the same day. Remember this conversion applies during standard time (November-March). When ADT is active (March-November), add 7 hours instead.
What should I know about scheduling across HST and AST?
Hawaii is 6 hours behind the Atlantic region during AST, making coordination similar to EDT but with slight differences. Morning AST times (9-11 AM) correspond to early morning HST times (3-5 AM), and late afternoon AST (3-5 PM) corresponds to morning HST (9-11 AM). For regular business coordination, early morning AST calls (7-9 AM) work well with Hawaii (1-3 AM HST for early risers, or 1-3 PM HST for afternoon workers).
Pro Tips
- • AST is always 6 hours ahead of HST during standard time (November-March). During daylight saving, ADT is 7 hours ahead.
- • Hawaii does not observe daylight saving time, so HST is consistent year-round while AST/ADT changes twice annually.
- • Morning AST (9-11 AM) aligns well with early morning HST (3-5 AM) for early risers or with afternoon HST (3-5 PM) for evening workers.
- • Early morning AST calls (7-9 AM) work for Hawaii afternoon schedules (1-3 PM HST), allowing both regions to coordinate during business-friendly hours.
- • Use 24-hour time format when communicating across HST-AST to eliminate AM/PM confusion, especially around morning/evening transitions.
- • Business and tourism coordination between Hawaii and the Atlantic region requires careful scheduling due to the significant time difference.