HST to GMT Converter
Convert time between Hawaii Standard Time (HST) and Greenwich Mean Time (GMT)
Hawaii Standard Time (HST)
Greenwich Mean Time (GMT)
Time Difference
Greenwich Mean Time (GMT) is 0 hours ahead of Hawaii Standard Time (HST)
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Select Time
Quick Reference
| HST | GMT |
|---|---|
| 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 GMT Time Conversion
Converting time from Hawaii Standard Time (HST) to Greenwich Mean Time (GMT) is essential for Hawaii to UK coordination. HST is UTC-10, while GMT is UTC+0, making GMT 10 hours ahead of HST.
This conversion is crucial for business operations coordinating between Hawaii (one of the most remote US states) and the United Kingdom, as well as international communications. Hawaii's unique year-round standard time (no daylight saving) simplifies scheduling.
Common Use Cases for HST to GMT Conversion
Business & Work
- Scheduling meetings between Hawaii and UK offices
- Coordinating business operations across vast distances
- Planning international project collaborations
Personal & Travel
- Planning travel between Hawaii and UK
- Coordinating with UK family and friends from Hawaii
- Scheduling virtual events for Hawaii-UK audiences
Time Zone Information
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, Kahului, Kailua-Kona
- Coverage: Hawaii (all islands)
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
Quick Reference: HST to GMT
Remember: GMT is always 10 hours ahead of HST (11 hours during British Summer Time)
Frequently Asked Questions
What is the time difference between HST and GMT?
Hawaii Standard Time (HST) is UTC-10, while GMT (Greenwich Mean Time) is UTC+0, making GMT 10 hours ahead of HST. When it is 12:00 PM (noon) in Hawaii (HST), it is 10:00 PM the same day in London (GMT).
Does Hawaii observe daylight saving time?
No, Hawaii does not observe daylight saving time. Hawaii Standard Time remains UTC-10 year-round, making it one of the few US states that does not switch to daylight saving time. This means HST has a consistent 10-hour difference with GMT throughout the year.
Does GMT observe daylight saving time?
No, GMT (Greenwich Mean Time) does not observe daylight saving time year-round. However, the UK uses BST (British Summer Time) during daylight saving periods (late March to late October). GMT remains UTC+0 and serves as a global standard reference throughout the year.
What is the time difference between HST and GMT during British Summer Time?
During British Summer Time (BST) from late March to late October, the UK is UTC+1 while Hawaii remains at UTC-10. This makes BST 11 hours ahead of HST during those months. The difference changes from 10 hours to 11 hours during the BST period.
How do I convert HST to GMT manually?
To convert HST to GMT, simply add 10 hours to the HST time. For example, if it is 3:00 PM HST, the corresponding GMT time would be 1:00 AM (midnight) the next day (15:00 + 10 hours = 25:00 or 01:00 next day). If the result exceeds 24 hours, subtract 24 hours and add 1 day.
Why is understanding HST to GMT conversion important?
Understanding HST to GMT conversion is crucial for coordinating with teams in Hawaii and the UK/Europe, international travel planning, virtual meetings across the Pacific, and managing global business operations. The 10-hour difference makes accurate conversion essential for scheduling and business coordination from across the world's largest ocean.
Pro Tips
- • Hawaii does not observe daylight saving time, making HST consistent at UTC-10 year-round unlike most US states. This simplifies scheduling but means you need to account for GMT changing to BST twice yearly.
- • GMT is equivalent to UTC (Coordinated Universal Time) and serves as the global reference time used for aviation and international business.
- • When the UK observes BST (late March to late October), Hawaii is 11 hours behind instead of 10 hours. Be aware of these transition dates when scheduling international meetings.
- • When scheduling international meetings between Hawaii and UK, early morning HST (7-8 AM) aligns with 5-6 PM GMT the same day, making it ideal for both regions during winter months.
- • Use a converter like this one for daylight saving transitions in the UK to avoid miscalculations when GMT switches to BST, as Hawaii remains constant.
- • Hawaii's unique timezone position (UTC-10 year-round) makes it one of the last places to enter a new day globally, which is why it's popular for international deadlines in business and finance.
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