HST to MDT
+4hHST
HSTSOURCEMDT
MDTGreen rows indicate typical business hours (9 AM - 5 PM)
HST and MDT on the World Map
The map below highlights the HST (Hawaii Standard Time) and MDT (Mountain Daylight Time) timezone regions across the globe.
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).
MDT – Mountain Daylight Time
UTC-06:00Mountain Daylight Time (MDT) is the daylight saving offset in the Mountain Time Zone, 6 hours behind UTC.
- •MDT shares the same offset as CST (UTC-06:00).
- •Arizona does not switch to MDT, remaining on MST.
HST vs MDT: Offsets, DST and Best Call Times
HST runs on Hawaii Standard Time (HST) at UTC-10:00. MDT runs on Mountain Daylight Time (MDT) at UTC-06:00. That puts HST 4 hours ahead of MDT — a difference of +4h at the current offsets.
In practice, when it is 9:00 AM in HST it is 1:00 PM in MDT. Midnight in HST is 4:00 AM in MDT. Neither zone observes daylight saving time, so the offset between them stays constant all year.
HST to MDT time conversion table
| HST (HST) | MDT (MDT) | Day |
|---|---|---|
| 12:00 AM | 4:00 AM | same day |
| 6:00 AM | 10:00 AM | same day |
| 7:00 AM | 11:00 AM | same day |
| 8:00 AM | 12:00 PM | same day |
| 9:00 AM | 1:00 PM | same day |
| 12:00 PM | 4:00 PM | same day |
| 3:00 PM | 7:00 PM | same day |
| 5:00 PM | 9:00 PM | same day |
| 6:00 PM | 10:00 PM | same day |
| 9:00 PM | 1:00 AM | next day |
Why people convert HST to MDT time
- Scheduling a call from HST to MDT: a 10:00 AM start in HST lands at 2:00 PM in MDT, so you can confirm the slot without doing the arithmetic yourself.
- Finding shared working hours: both HST and MDT are inside the 9-to-5 working day between 9:00 AM and 1:00 PM HST time (1:00 PM–5:00 PM MDT). That is roughly 4 hours of usable overlap.
- Keeping family and friends in sync: knowing that 8:00 PM in HST is 12:00 AM in MDT makes it easy to avoid calling at 3 AM.
- Always state the zone abbreviation, not just the hour. "3:00 PM HST" is unambiguous; "3 PM" across a +4h gap is not.
- Block 9:00 AM–1:00 PM HST as the recurring meeting window if you work primarily from HST and need MDT colleagues present.
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.
About MDT (Mountain Daylight Time)
Mountain Daylight Time (MDT) is observed during summer months in the Mountain Time Zone, except in Arizona which stays on MST year-round. MDT aligns with Central Standard Time (CST) at UTC-06:00.
Best time to call between HST and MDT
Both HST and MDT sit inside the 9 AM – 5 PM working day between 9:00 AM–1:00 PM HST, which is 1:00 PM–5:00 PM MDT. That gives roughly 4 hours of shared time — the safest window for a live call or meeting.
Business hours overlap
HST and MDT overlap for about 4 hours during the working day — enough for meetings if you avoid the edges of the window.
HST is 4 hours ahead of MDT (HST UTC-10:00 → MDT UTC-06:00). The shared working window is 9:00 AM–1:00 PM HST. Remember to re-check around daylight-saving transitions.
🕐 Daylight Saving Time Info
HST
Does not observe DST
MDT
☀ Currently in DST
Standard: UTC-07:00 · DST: UTC-06:00
Clocks fall back on Sun, Nov 1, 2026
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 HST and MDT?
HST (HST, UTC-10:00) is 4 hours ahead of MDT (MDT, UTC-06:00). The gap is currently +4h.
How do I convert HST time to MDT time?
Add +4h to HST local time. For example, 9:00 AM in HST is 1:00 PM in MDT.
What time is it in MDT right now?
MDT uses MDT at UTC-06:00. Use the live converter at the top of this page — it updates in real time and already accounts for the +4h offset from HST.
What is the best time to call MDT from HST?
Call between 9:00 AM and 1:00 PM HST — that maps to 1:00 PM–5:00 PM MDT and keeps both parties inside the working day.
Which is ahead, HST or MDT?
HST is 4 hours ahead of MDT. When it is 12:00 PM in HST it is 4:00 PM in MDT.
Does daylight saving time affect the HST–MDT difference?
Neither zone observes daylight saving time, so the +4h offset between HST and MDT is fixed all year.
Which other cities share HST's time zone?
HST also covers Honolulu, Hilo, Kailua, Pearl City, Kapolei.
Which countries use HST, HST's zone?
HST is used in United States (Hawaii).
Is there a day difference between HST and MDT?
Not normally. The +4h gap only pushes the date over for late-evening times.
What is the time difference between HST and MDT?
MDT is +4h from HST.
What timezone is HST in?
HST operates on its local timezone.
What timezone is MDT in?
MDT operates on its local timezone.
Which countries use HST (Hawaii Standard Time)?
HST is used in United States (Hawaii).
Does HST observe daylight saving time?
No, HST does not observe daylight saving time and remains at UTC-10:00 year-round.
What are some interesting facts about HST?
Hawaii does not observe daylight saving time. HST is 5 hours behind EST in winter and 6 hours behind EDT in summer.
Which cities are in the MDT timezone?
Major cities in the MDT timezone include Denver, Calgary, Edmonton, Salt Lake City, Boise.
What is the UTC offset for MDT?
Mountain Daylight Time (MDT) is at UTC-06:00. During daylight saving time, it shifts to MST.
What should I know about the MDT timezone?
MDT shares the same offset as CST (UTC-06:00). Arizona does not switch to MDT, remaining on MST.
When is it midnight in HST, what time is it in MDT?
When it is 12:00 AM (midnight) in HST (HST), it is +4h later in MDT (MDT).
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See every conversion from HST →·See every conversion from MDT →