MST to HST
-3hMST
MSTSOURCEHST
HSTGreen rows indicate typical business hours (9 AM - 5 PM)
MST and HST on the World Map
The map below highlights the MST (Mountain Standard Time) and HST (Hawaii Standard Time) timezone regions across the globe.
MST – Mountain Standard Time
UTC-07:00Mountain Standard Time (MST) is the time zone for the Mountain region of North America, 7 hours behind UTC.
- •Arizona does not observe daylight saving time, staying on MST year-round.
- •The Navajo Nation in Arizona does observe DST, unlike the rest of the state.
- •Denver, the 'Mile High City', is the largest city fully in MST.
- •MST covers 6 US states entirely and parts of several others.
HST – Hawaii Standard Time
UTC-10:00Hawaii Standard Time (HST) is the time zone for the Hawaiian Islands, 10 hours behind UTC.
- •Hawaii does not observe daylight saving time.
- •HST is 5 hours behind EST in winter and 6 hours behind EDT in summer.
- •Hawaii is one of only two US states that don't observe DST (the other is Arizona).
Everything You Need to Know About MST and HST Time
MST runs on Mountain Standard Time (MST) at UTC-07:00. HST runs on Hawaii Standard Time (HST) at UTC-10:00. That puts MST 3 hours behind HST — a difference of -3h at the current offsets.
In practice, when it is 9:00 AM in MST it is 6:00 AM in HST. Midnight in MST is 9:00 PM in HST. Neither zone observes daylight saving time, so the offset between them stays constant all year.
MST to HST time conversion table
| MST (MST) | HST (HST) | Day |
|---|---|---|
| 12:00 AM | 9:00 PM | previous day |
| 6:00 AM | 3:00 AM | same day |
| 7:00 AM | 4:00 AM | same day |
| 8:00 AM | 5:00 AM | same day |
| 9:00 AM | 6:00 AM | same day |
| 12:00 PM | 9:00 AM | same day |
| 3:00 PM | 12:00 PM | same day |
| 5:00 PM | 2:00 PM | same day |
| 6:00 PM | 3:00 PM | same day |
| 9:00 PM | 6:00 PM | same day |
Why people convert MST to HST time
- Scheduling a call from MST to HST: a 10:00 AM start in MST lands at 7:00 AM in HST, so you can confirm the slot without doing the arithmetic yourself.
- Finding shared working hours: both MST and HST are inside the 9-to-5 working day between 12:00 PM and 5:00 PM MST time (9:00 AM–2:00 PM HST). That is roughly 5 hours of usable overlap.
- Coordinating a MST-based team with HST contacts: quoting times in the other side's local clock — not your own — removes the single biggest source of missed meetings.
- Always state the zone abbreviation, not just the hour. "3:00 PM MST" is unambiguous; "3 PM" across a -3h gap is not.
- Block 12:00 PM–5:00 PM MST as the recurring meeting window if you work primarily from MST and need HST colleagues present.
About MST (Mountain Standard Time)
Mountain Standard Time (MST) covers the Rocky Mountain region of the United States and Canada. Arizona is notable for not observing daylight saving time, staying on MST year-round (except the Navajo Nation). The time zone includes major cities like Denver, Phoenix, Calgary, and Salt Lake City. During summer, most areas switch to Mountain Daylight Time (MDT, UTC-06:00).
About HST (Hawaii Standard Time)
Hawaii Standard Time (HST) is used in the state of Hawaii and does not observe daylight saving time. This makes HST one of the most consistent time zones in the US. The Hawaiian Islands are among the last places on Earth to see a new calendar day.
Best time to call between MST and HST
Both MST and HST sit inside the 9 AM – 5 PM working day between 12:00 PM–5:00 PM MST, which is 9:00 AM–2:00 PM HST. That gives roughly 5 hours of shared time — the safest window for a live call or meeting.
Business hours overlap
MST and HST share 5 hours of working-hours overlap (12:00 PM–5:00 PM MST), so scheduling a live meeting is straightforward.
MST is 3 hours behind HST (MST UTC-07:00 → HST UTC-10:00). The shared working window is 12:00 PM–5:00 PM MST. Remember to re-check around daylight-saving transitions.
🕐 Daylight Saving Time Info
MST
☀ Currently in DST
Standard: UTC-07:00 · DST: UTC-06:00
Clocks fall back on Sun, Nov 1, 2026
HST
Does not observe DST
Learn More About Time
Dive deeper into the fascinating world of timekeeping, time zones, and how they shape our global society:
Frequently Asked Questions
What is the time difference between MST and HST?
MST (MST, UTC-07:00) is 3 hours behind HST (HST, UTC-10:00). The gap is currently -3h.
How do I convert MST time to HST time?
Add -3h to MST local time. For example, 9:00 AM in MST is 6:00 AM in HST.
What time is it in HST right now?
HST uses HST at UTC-10:00. Use the live converter at the top of this page — it updates in real time and already accounts for the -3h offset from MST.
What is the best time to call HST from MST?
Call between 12:00 PM and 5:00 PM MST — that maps to 9:00 AM–2:00 PM HST and keeps both parties inside the working day.
Which is behind, MST or HST?
MST is 3 hours behind HST. When it is 12:00 PM in MST it is 9:00 AM in HST.
Does daylight saving time affect the MST–HST difference?
Neither zone observes daylight saving time, so the -3h offset between MST and HST is fixed all year.
Which other cities share MST's time zone?
MST also covers Denver, Phoenix, Salt Lake City, Calgary, Edmonton, Albuquerque, El Paso, Tucson and 2 more.
Which countries use MST, MST's zone?
MST is used in United States (Mountain), Canada (Alberta), Mexico (Chihuahua, Sonora).
Is there a day difference between MST and HST?
Not normally. The -3h gap only pushes the date over the previous day.
What is the time difference between MST and HST?
HST is -3h from MST.
What timezone is MST in?
MST operates on its local timezone.
What timezone is HST in?
HST operates on its local timezone.
Which countries use MST (Mountain Standard Time)?
MST is used in United States (Mountain), Canada (Alberta), Mexico (Chihuahua, Sonora).
Does MST observe daylight saving time?
Yes, MST switches to MDT during summer months.
What are some interesting facts about MST?
Arizona does not observe daylight saving time, staying on MST year-round. The Navajo Nation in Arizona does observe DST, unlike the rest of the state.
Which cities are in the HST timezone?
Major cities in the HST timezone include Honolulu, Hilo, Kailua, Pearl City, Kapolei.
What is the UTC offset for HST?
Hawaii Standard Time (HST) is at UTC-10:00.
What should I know about the HST timezone?
Hawaii does not observe daylight saving time. HST is 5 hours behind EST in winter and 6 hours behind EDT in summer.
When is it midnight in MST, what time is it in HST?
When it is 12:00 AM (midnight) in MST (MST), it is -3h later in HST (HST).
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See every conversion from MST →·See every conversion from HST →