HST to UTC
+10hHST
HSTSOURCEUTC
UTCGreen rows indicate typical business hours (9 AM - 5 PM)
HST and UTC on the World Map
The map below highlights the HST (Hawaii Standard Time) and UTC (Coordinated Universal 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).
UTC – Coordinated Universal Time
UTC+00:00Coordinated Universal Time (UTC) is the world's primary time standard, used as the basis for civil time worldwide.
- •UTC is the basis for all civil time zones worldwide.
- •The abbreviation 'UTC' is a compromise between English (CUT) and French (TUC).
- •UTC is based on atomic clocks and is accurate to within a nanosecond per day.
- •Servers and databases worldwide store timestamps in UTC to avoid timezone confusion.
- •Leap seconds are occasionally added to UTC to keep it aligned with Earth's rotation.
Comparing Time Zones: HST and UTC
HST runs on Hawaii Standard Time (HST) at UTC-10:00. UTC runs on Coordinated Universal Time (UTC) at UTC+00:00. That puts HST 10 hours ahead of UTC — a difference of +10h at the current offsets.
In practice, when it is 9:00 AM in HST it is 7:00 PM in UTC. Midnight in HST is 10:00 AM in UTC. Neither zone observes daylight saving time, so the offset between them stays constant all year.
HST to UTC time conversion table
| HST (HST) | UTC (UTC) | Day |
|---|---|---|
| 12:00 AM | 10:00 AM | same day |
| 6:00 AM | 4:00 PM | same day |
| 7:00 AM | 5:00 PM | same day |
| 8:00 AM | 6:00 PM | same day |
| 9:00 AM | 7:00 PM | same day |
| 12:00 PM | 10:00 PM | same day |
| 3:00 PM | 1:00 AM | next day |
| 5:00 PM | 3:00 AM | next day |
| 6:00 PM | 4:00 AM | next day |
| 9:00 PM | 7:00 AM | next day |
Why people convert HST to UTC time
- Scheduling a call from HST to UTC: a 10:00 AM start in HST lands at 8:00 PM in UTC, so you can confirm the slot without doing the arithmetic yourself.
- Handling a +10h gap: HST and UTC have no overlap inside a normal 9-to-5 day, so real-time meetings need an early-morning or late-evening slot on one side. 9:00 AM in UTC is 7:00 PM in HST.
- Coordinating a HST-based team with UTC 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 HST" is unambiguous; "3 PM" across a +10h gap is not.
- With a +10h gap there is no shared 9-to-5 window, so alternate the early start: one week HST takes the early slot, the next week UTC does.
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 UTC (Coordinated Universal Time)
Coordinated Universal Time (UTC) is the primary time standard by which the world regulates clocks and time. It is effectively the successor to GMT and is based on International Atomic Time with leap seconds added to keep it synchronized with Earth's rotation. UTC is used in aviation, computing, navigation, weather forecasting, and the International Space Station. Most programming languages and databases store timestamps in UTC.
Best time to call between HST and UTC
With a +10h offset there is no overlap inside a normal 9 AM – 5 PM day. UTC opens at 9:00 AM UTC, which is 7:00 PM in HST, so real-time calls need an early-morning or late-evening slot on one side.
Business hours overlap
HST and UTC have no shared working hours because of the +10h gap. Teams need to alternate early starts or rely on asynchronous handovers.
HST is 10 hours ahead of UTC (HST UTC-10:00 → UTC UTC+00:00). There is no shared 9-to-5 window, so plan around an early or late slot. Remember to re-check around daylight-saving transitions.
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 UTC?
HST (HST, UTC-10:00) is 10 hours ahead of UTC (UTC, UTC+00:00). The gap is currently +10h.
How do I convert HST time to UTC time?
Add +10h to HST local time. For example, 9:00 AM in HST is 7:00 PM in UTC.
What time is it in UTC right now?
UTC uses UTC at UTC+00:00. Use the live converter at the top of this page — it updates in real time and already accounts for the +10h offset from HST.
What is the best time to call UTC from HST?
There is no shared working-hours window because of the +10h gap. The closest option is 1:00 PM in HST, which is 11:00 PM in UTC.
Which is ahead, HST or UTC?
HST is 10 hours ahead of UTC. When it is 12:00 PM in HST it is 10:00 PM in UTC.
Does daylight saving time affect the HST–UTC difference?
Neither zone observes daylight saving time, so the +10h offset between HST and UTC 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 UTC?
Not normally. The +10h gap only pushes the date over for late-evening times.
What is the time difference between HST and UTC?
UTC is +10h from HST.
What timezone is HST in?
HST operates on its local timezone.
What timezone is UTC in?
UTC 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 UTC timezone?
Major cities in the UTC timezone include London, Dublin, Reykjavik, Accra, Lisbon, Dakar.
What is the UTC offset for UTC?
Coordinated Universal Time (UTC) is at UTC+00:00.
What should I know about the UTC timezone?
UTC is the basis for all civil time zones worldwide. The abbreviation 'UTC' is a compromise between English (CUT) and French (TUC).
When is it midnight in HST, what time is it in UTC?
When it is 12:00 AM (midnight) in HST (HST), it is +10h later in UTC (UTC).
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See every conversion from HST →·See every conversion from UTC →