GMT to HST Converter
Convert time between Greenwich Mean Time (GMT) and Hawaii Standard Time (HST)
Greenwich Mean Time (GMT)
Hawaii Standard Time (HST)
Time Difference
Hawaii Standard Time (HST) is 0 hours ahead of Greenwich Mean Time (GMT)
Select Date
Select Time
Quick Reference
| GMT | HST |
|---|---|
| 02:00 | 16:00 |
| 04:00 | 18:00 |
| 06:00 | 20:00 |
| 08:00 | 22:00 |
| 10:00 | 00:00 |
| 12:00 | 02:00 |
| 14:00 | 04:00 |
| 16:00 | 06:00 |
| 18:00 | 08:00 |
| 20:00 | 10:00 |
| 22:00 | 12:00 |
| 00:00 | 14:00 |
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 GMT to HST Time Conversion
Converting time from Greenwich Mean Time (GMT) to Hawaii Standard Time (HST) is essential for UK to Hawaii coordination. GMT is UTC+0, while HST is UTC-10, making HST 10 hours behind GMT.
This conversion is crucial for international business operations between the United Kingdom and Hawaii, including tourism, technology, and military operations. Hawaii is unique in not observing daylight saving time, keeping HST constant year-round, though the GMT/BST transition in the UK can affect the actual offset.
Common Use Cases for GMT to HST Conversion
Business & Work
- Scheduling UK to Hawaii business meetings and calls
- Coordinating London and Honolulu tourism operations
- Managing international technology and research projects
- Planning conference calls with distributed teams
Personal & Travel
- Planning travel from UK to Hawaii
- Coordinating with Hawaii family and friends from UK
- Scheduling virtual events and online meetings for UK-Hawaii audiences
- Arranging online classes or training sessions
Time Zone Information
Greenwich Mean Time (GMT)
- UTC Offset: UTC+0 (UTC+1 during BST)
- IANA Timezone: Europe/London
- Daylight Saving: Last Sunday in March to Last Sunday in October
- Major Cities: London, Edinburgh, Cardiff, Belfast, Dublin
- Coverage: United Kingdom and Ireland
Hawaii Standard Time (HST)
- UTC Offset: UTC-10 (no daylight saving)
- IANA Timezone: Pacific/Honolulu
- Daylight Saving: None - Hawaii does not observe daylight saving time
- Major Cities: Honolulu, Hilo, Maui, Kauai
- Coverage: Hawaii islands
Quick Reference: GMT to HST
Remember: HST is always 10 hours behind GMT (or 11 hours when UK observes BST). Hawaii does not observe daylight saving time, so HST remains constant year-round.
Frequently Asked Questions
What is the time difference between GMT and HST?
Greenwich Mean Time (GMT) is UTC+0, while Hawaii Standard Time (HST) is UTC-10. This means GMT is 10 hours ahead of HST. When it's 12:00 PM (noon) in London (GMT), it's 2:00 AM in Honolulu (HST).
Does Hawaii observe daylight saving time?
No, Hawaii does not observe daylight saving time. Hawaii Standard Time (HST) remains at UTC-10 throughout the entire year. This is one of the few US states that does not switch to daylight saving time, along with Arizona, Puerto Rico, and US territories.
Does the UK use GMT year-round?
No, the UK switches between GMT (UTC+0) in winter and BST (British Summer Time, UTC+1) in summer. BST is active from the last Sunday in March to the last Sunday in October. This means when the UK observes BST, the time difference to HST becomes 11 hours instead of 10.
How does the time difference vary throughout the year?
Since Hawaii does not observe daylight saving time, the time difference with GMT varies based only on whether the UK is on GMT or BST. From late October to late March (UK on GMT), the difference is 10 hours. From late March to late October (UK on BST), the difference is 11 hours.
What are the best times to schedule calls between UK and Hawaii?
The large 10-hour time difference makes scheduling very challenging. Evening in the UK (6-8 PM GMT) overlaps with early morning in Hawaii (8-10 AM HST). For optimal business hours overlap, schedule meetings between 5-7 PM UK time (7-9 AM HST) or very early morning UK time (6-8 AM GMT, 8-10 PM HST previous day).
Why is GMT to HST conversion important?
GMT to HST conversion is essential for coordinating between the United Kingdom and Hawaii, a major hub for tourism, technology, and military operations. This conversion is vital for business operations, research collaborations, tourism coordination, and personal communications between these regions.
Pro Tips
- • The 10-hour difference is substantial - 12 PM in London equals 2 AM in Hawaii! Real-time communication is extremely challenging.
- • Hawaii does not observe daylight saving time, while the UK does. This means the offset varies between 10 and 11 hours depending on the UK's DST status.
- • For better UK-Hawaii meetings, consider scheduling in late UK afternoon (5-7 PM GMT) for early Hawaii morning (7-9 AM HST).
- • Early morning UK time (6-8 AM GMT) works for Hawaii evening/night (8-10 PM HST previous day) - useful for international teams wanting overlap.
- • Hawaii's fixed year-round time (always HST) makes it consistent, unlike US states that observe daylight saving time.
- • For 24/7 operations with UK-Hawaii teams, split-shift scheduling across both time zones is essential for continuous coverage.
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