HST to GMT Converter
Understanding HST and GMT Time Zones
Hawaii Standard Time (HST)
Hawaii Standard Time is observed in undefined and uses the offset UTC-10. Major cities in this time zone include Honolulu, Maui. This time zone serves a significant global region with important economic and cultural hubs.
Greenwich Mean Time (GMT)
Greenwich Mean Time operates at UTC+0, covering undefined. Key cities include London, Dublin, Lisbon. The 10-hour forward offset from HST means that when professionals in Honolulu start their workday at 9:00 AM, it is already 7:00 PM in London.
HST is also commonly referred to as Hawaii Time, Honolulu time, Hawaiian time. GMT is also known as London time, UK time, British time, England time. So if you are searching for Hawaii Time to London time, this is the same conversion as HST to GMT.
Complete HST to GMT Conversion Table
The table below shows every two-hour increment converted from Hawaii Standard Time to Greenwich Mean Time. Business hours (9 AM – 5 PM) are highlighted for easy scheduling reference.
| HST (Hawaii Standard Time) | GMT (Greenwich Mean Time) |
|---|---|
| 12:00 AM (00:00) | 10:00 AM (10:00) |
| 2:00 AM (02:00) | 12:00 PM (12:00) |
| 4:00 AM (04:00) | 2:00 PM (14:00) |
| 6:00 AM (06:00) | 4:00 PM (16:00) |
| 8:00 AM (08:00) | 6:00 PM (18:00) |
| 10:00 AM (10:00) | 8:00 PM (20:00) |
| 12:00 PM (12:00) | 10:00 PM (22:00) |
| 2:00 PM (14:00) | 12:00 AM (00:00) (next day) |
| 4:00 PM (16:00) | 2:00 AM (02:00) (next day) |
| 6:00 PM (18:00) | 4:00 AM (04:00) (next day) |
| 8:00 PM (20:00) | 6:00 AM (06:00) (next day) |
| 10:00 PM (22:00) | 8:00 AM (08:00) (next day) |
Times shown in 12-hour and 24-hour format. Last updated 2026-03-09.
Scheduling Between HST and GMT
For business scheduling, the optimal overlap window between HST and GMT falls roughly between 11:00 PM and 7:00 AM HST. This ensures both Honolulu and London teams are within standard working hours.
The large 10-hour gap between HST and GMT means that finding overlapping working hours requires compromise from at least one side. Consider adopting asynchronous workflows — recorded video updates, shared documents, and time-zone-aware project management tools — to supplement the limited real-time overlap.
Travel Between Honolulu and London
Travelers flying from Honolulu to London should adjust their sleep schedule 10 days before departure at a rate of one hour per day. For this significant time difference, gradual adjustment reduces jet lag dramatically.
Medical experts recommend allowing approximately one day of adjustment per hour of time difference. For the 10-hour shift between HST and GMT, plan for roughly one week of gradual adjustment for optimal performance.
Daylight Saving Time Considerations
During standard time months (November through March in the US), this offset is fixed. However, if either zone observes daylight saving time, the difference may temporarily shift by one hour during transition weeks in spring and autumn.
For the HST to GMT conversion specifically: HST (UTC-10) does not observe DST, while GMT (UTC+0) does observe DST. This means the offset between them changes by one hour seasonally — the usual 10-hour gap becomes 9 or 11 hours during DST transitions.
Related Time Zone Conversions
References & Resources
Frequently Asked Questions
HST (Hawaii Standard Time) is 10 hours behind GMT (Greenwich Mean Time). HST is UTC-10 and GMT is UTC+0.
When it is 12:00 PM (noon) in HST, it is 10:00 PM in GMT.
The best overlap for business hours is approximately 7:00 PM to 3:00 AM GMT, which corresponds to 9:00 AM to 5:00 PM in HST. Given the large gap, consider alternating between early and late meeting times.
During standard time months (November through March in the US), this offset is fixed. However, if either zone observes daylight saving time, the difference may temporarily shift by one hour during transition weeks in spring and autumn.