MST to HST Converter
Convert time between Mountain Standard Time (MST) and Hawaii Standard Time (HST)
Mountain Standard Time (MST)
Hawaii Standard Time (HST)
Time Difference
Hawaii Standard Time (HST) is 0 hours ahead of Mountain Standard Time (MST)
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Select Time
Quick Reference
| MST | HST |
|---|---|
| 19:00 | 16:00 |
| 21:00 | 18:00 |
| 23:00 | 20:00 |
| 01:00 | 22:00 |
| 03:00 | 00:00 |
| 05:00 | 02:00 |
| 07:00 | 04:00 |
| 09:00 | 06:00 |
| 11:00 | 08:00 |
| 13:00 | 10:00 |
| 15:00 | 12:00 |
| 17:00 | 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 MST to HST Time Conversion
Converting time between Mountain Standard Time (MST) and Hawaii Standard Time (HST) is essential for coordinating between the US Mountain region and Hawaii. MST is UTC-7 (standard time, typically November to March), while HST is UTC-10 (year-round, Hawaii does not observe daylight saving time). MST is 3 hours ahead of HST during standard time. When daylight saving time is active on the mainland (March-November), the Mountain region observes MDT (UTC-6), making it 4 hours ahead of HST.
This conversion is crucial for businesses operating between Denver, Salt Lake City, Phoenix, and Hawaii. Tech companies, tourism operations, government agencies, and enterprises coordinating mainland mountain region and island operations rely on accurate time conversions. Hawaii Standard Time is unique as it remains constant throughout the year without daylight saving adjustments. This makes the offset with mainland time zones inconsistent - during winter months (MST) the difference is 3 hours, but during summer months (MDT) the difference is 4 hours, requiring careful attention when scheduling calls and managing operations across both regions.
Common Use Cases for MST to HST Conversion
Business & Work
- Scheduling calls between Denver headquarters and Hawaii branch offices
- Coordinating business operations between Mountain region and Hawaiian locations
- Managing tourist operations and hospitality services across the mainland and islands
- Planning conference calls for companies with presence in both regions
Personal & Travel
- Coordinating with family and friends in Hawaii from the Mountain region
- Planning travel between Mountain region and Hawaiian destinations
- Scheduling virtual meetings with Hawaii-based relatives or business partners
- Arranging online collaboration with Hawaii-based colleagues
Time Zone Information
Mountain Standard Time (MST)
- UTC Offset: UTC-7
- IANA Timezone: America/Denver
- Daylight Saving: Standard time (first Sunday in November to second Sunday in March)
- Major Cities: Denver, Salt Lake City, Albuquerque, Boise, Las Vegas
- Coverage: Mountain United States and Canada (winter months)
Hawaii Standard Time (HST)
- UTC Offset: UTC-10
- IANA Timezone: Pacific/Honolulu
- Daylight Saving: No daylight saving time (consistent year-round)
- Major Cities: Honolulu, Hilo, Kailua, Maui, Kauai
- Coverage: All Hawaiian islands (consistent year-round)
Quick Reference: MST to HST
Remember: MST is 3 hours ahead of HST (during winter). When daylight saving time begins (second Sunday in March) and MST becomes MDT, the difference increases to 4 hours. Hawaii does not observe daylight saving time.
Frequently Asked Questions
What is the time difference between MST and HST?
Mountain Standard Time (MST) is UTC-7, while Hawaii Standard Time (HST) is UTC-10. MST is 3 hours ahead of HST. When it's 9:00 AM in Denver (MST), it's 6:00 AM the same day in Honolulu (HST).
When is MST active and how does it affect Hawaii coordination?
MST is observed from the first Sunday in November to the second Sunday in March. During this period, the Mountain region is 3 hours ahead of Hawaii. From March to November, when the Mountain region observes MDT (UTC-6), the difference is 4 hours. This makes winter coordination (MST season) have a smaller time gap than summer coordination.
Does Hawaii observe daylight saving time like MST does?
No, Hawaii does not observe daylight saving time. Hawaii Standard Time (HST) remains UTC-10 year-round. This is why the time difference between Hawaii and the mainland varies - the mainland changes its clocks twice per year while Hawaii stays constant. MST is specifically the winter offset for the Mountain region.
What major cities are in MST and HST timezones?
MST covers major Mountain region cities including Denver, Salt Lake City, Albuquerque, Boise, and Las Vegas during winter months. HST covers all Hawaiian islands with major cities being Honolulu, Hilo, Kailua, Waihuku, and Kaneohe. These regions represent the US Mountain region during winter and the Hawaiian Islands.
What are the best times to schedule calls between MST and HST regions?
The 3-hour difference during MST season provides good overlap. Morning hours in MST (8-10 AM) correspond to early morning in HST (5-7 AM), and late morning MST (10 AM-12 PM) corresponds to morning HST (7-9 AM). Afternoon MST (3-5 PM) aligns well with late morning/midday HST (12-2 PM), making this an ideal window for winter business coordination.
How does winter (MST) coordination differ from summer (MDT) coordination with Hawaii?
During winter (November-March, MST season), the Mountain region is 3 hours ahead of Hawaii, providing decent overlap for business hours. During summer (March-November, MDT season), the difference increases to 4 hours, making the time gap larger. Many businesses adjust their schedules seasonally to accommodate these changes, with winter being more favorable for synchronous communication.
Pro Tips
- • MST is always 3 hours ahead of HST during winter months (November-March).
- • When daylight saving time begins (second Sunday in March), MST becomes MDT and the difference increases to 4 hours.
- • Morning hours (8-10 AM MST) correspond to early morning HST times (5-7 AM), ideal for coordinating business operations.
- • Hawaii does not observe daylight saving time, so HST is consistent year-round while MST changes once per season.
- • For long-term projects spanning both seasons, account for the time difference change when MST transitions to MDT in March.
- • Afternoon MST (3-5 PM) aligns well with midday HST (12-2 PM), providing excellent overlap for winter business calls and coordination.
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