HST to UTC Converter
Convert time between Hawaii Standard Time (HST) and Coordinated Universal Time (UTC)
Hawaii Standard Time (HST)
Coordinated Universal Time (UTC)
Time Difference
Coordinated Universal Time (UTC) is 0 hours ahead of Hawaii Standard Time (HST)
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Select Time
Quick Reference
| HST | UTC |
|---|---|
| 16:00 | 02:00 |
| 18:00 | 04:00 |
| 20:00 | 06:00 |
| 22:00 | 08:00 |
| 00:00 | 10:00 |
| 02:00 | 12:00 |
| 04:00 | 14:00 |
| 06:00 | 16:00 |
| 08:00 | 18:00 |
| 10:00 | 20:00 |
| 12:00 | 22:00 |
| 14:00 | 00:00 |
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 UTC Time Conversion
Converting time between Hawaii Standard Time (HST) and Coordinated Universal Time (UTC) is essential for international scheduling and coordination. HST is UTC-10 (year-round, no daylight saving time), while UTC is the universal reference standard with UTC+0. HST is 10 hours behind UTC, making this conversion crucial for global business operations, international travel coordination, and communications with partners worldwide.
This time zone converter uses the IANA timezone database to ensure accurate calculations. Hawaii's unique position of not observing daylight saving time makes HST consistently UTC-10 throughout the year. Whether you're scheduling meetings with international partners, managing global business operations, coordinating international travel, or managing scientific research, our converter provides reliable results for global coordination. Hawaii's geographic isolation and unique DST policy make accurate timezone conversion especially important.
Common Use Cases for HST to UTC Conversion
Business & Work
- Scheduling international calls between Hawaii and global partners year-round
- Coordinating with teams in Europe, Asia, Africa, and North America from Hawaii
- Managing international business operations and meetings from Hawaiian locations
- Synchronizing business processes across multiple international time zones from Hawaii
Personal & Travel
- Coordinating with family and friends across different continents
- Planning international travel and connecting flights from Hawaii
- Scheduling online events with global participants
- Understanding UTC times for international sports events and broadcasts
Time Zone Information
Hawaii Standard Time (HST)
- UTC Offset: UTC-10 (year-round, no daylight saving)
- IANA Timezone: Pacific/Honolulu
- Daylight Saving: No daylight saving time (consistent year-round)
- Major Cities: Honolulu, Hilo, Kailua, Maui, Kauai, Kona
- Coverage: All Hawaiian islands (Big Island, Maui, Oahu, Kauai, Molokai, Lanai, Niihau, Kahoolawe)
Coordinated Universal Time (UTC)
- UTC Offset: UTC+0 (year-round, no daylight saving)
- IANA Timezone: UTC
- Daylight Saving: No daylight saving time (universal reference)
- Major Cities: Used globally for aviation, military, maritime, science, and international business
- Coverage: Universal reference timezone for global coordination
Quick Reference: HST to UTC
Remember: HST is always 10 hours behind UTC. Hawaii does not observe daylight saving time, so this conversion remains consistent throughout the entire year. This 10-hour offset is consistent whether it's summer or winter, making HST one of the simplest US timezones to convert to UTC.
Frequently Asked Questions
What is the time difference between HST and UTC?
Hawaii Standard Time (HST) is UTC-10, while UTC is the reference standard (UTC+0). This means HST is 10 hours behind UTC. When it's 1:00 PM in Honolulu (HST), it's 11:00 PM UTC (same day). Unlike most US timezones, Hawaii does not observe daylight saving time and remains on HST year-round.
Does Hawaii observe daylight saving time?
No, Hawaii does not observe daylight saving time. Hawaii Standard Time (HST) remains UTC-10 throughout the entire year. This is unique among US states and territories. Most of Arizona also does not observe daylight saving time, but Hawaii is one of the few places that maintains the same offset year-round, making scheduling consistent but requiring careful conversion when dealing with mainland US timezones.
How is HST to UTC different from other US timezone conversions?
HST is unique because it does not change throughout the year, remaining UTC-10 year-round. Most mainland US timezones shift between standard and daylight time. This means HST maintains a consistent 10-hour difference with UTC, unlike Eastern (EST/EDT), Central (CST/CDT), and Mountain (MST/MDT) timezones that vary by 1 hour seasonally. This makes HST to UTC conversion simpler and more predictable.
What are the major cities in the HST timezone?
The Hawaii Standard Time zone covers the entire Hawaiian archipelago, including major cities like Honolulu, Hilo, Kailua, Maui, Kauai, Lahaina, and Kona. Hawaii is the southernmost US state and the most isolated, located about 2,400 miles from the mainland. This geographic isolation is one reason Hawaii maintains its own timezone without daylight saving time.
Why would I need to convert HST to UTC?
UTC conversion is essential for international scheduling, aviation, maritime operations, scientific research, and global business coordination. UTC is the worldwide standard for synchronizing activities across time zones. If you're scheduling meetings with Europe, Asia, Africa, or other international regions from Hawaii, using UTC eliminates confusion. Hawaii's large 10-hour offset from UTC makes precise conversion especially important for business operations.
How do I convert HST to UTC accurately?
To convert HST to UTC, subtract 10 hours from the HST time. For example: 3:00 PM HST equals 1:00 AM UTC (next day), and 8:00 AM HST equals 6:00 PM UTC (same day). Since Hawaii does not observe daylight saving time, this conversion remains consistent year-round. The 10-hour difference means that early morning in Hawaii corresponds to late evening the previous day in UTC.
Pro Tips
- • UTC is always the global reference - use UTC for scheduling international calls, especially with Europe, Asia, and other continents to avoid confusion with daylight saving time variations.
- • Hawaii does not observe daylight saving time, which means HST remains UTC-10 year-round. This consistency makes HST unique among US timezones and simplifies conversion, but requires awareness when coordinating with mainland timezones that do change.
- • When coordinating with UTC-based teams, always specify both the local time (HST) and UTC time to prevent scheduling errors. The large 10-hour difference can be confusing without explicit notation.
- • Hawaii is one of the few places where you don't need to worry about daylight saving transitions affecting HST-UTC conversions. This makes it simpler but also means you must account for mainland DST changes when coordinating with US partners.
- • For international business, aviation, maritime operations, and scientific research, use UTC as the standard timezone for all correspondence, logs, schedules, and official timekeeping to ensure global clarity.
- • Quick mental math: HST midnight (00:00) is 10:00 AM UTC the same day. Noon HST (12:00) is 10:00 PM UTC. This consistent 10-hour offset makes mental conversion straightforward throughout the year.
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