UTC to HST
-10hUTC
UTCSOURCEHST
HSTGreen rows indicate typical business hours (9 AM - 5 PM)
UTC and HST on the World Map
The map below highlights the UTC (Coordinated Universal Time) and HST (Hawaii Standard Time) timezone regions across the globe.
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.
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 to HST Time Difference – Complete Guide
UTC runs on Coordinated Universal Time (UTC) at UTC+00:00. HST runs on Hawaii Standard Time (HST) at UTC-10:00. That puts UTC 10 hours behind HST — a difference of -10h at the current offsets.
In practice, when it is 9:00 AM in UTC it is 11:00 PM in HST on the previous day. Midnight in UTC is 2:00 PM in HST. Neither zone observes daylight saving time, so the offset between them stays constant all year.
UTC to HST time conversion table
| UTC (UTC) | HST (HST) | Day |
|---|---|---|
| 12:00 AM | 2:00 PM | previous day |
| 6:00 AM | 8:00 PM | previous day |
| 7:00 AM | 9:00 PM | previous day |
| 8:00 AM | 10:00 PM | previous day |
| 9:00 AM | 11:00 PM | previous day |
| 12:00 PM | 2:00 AM | same day |
| 3:00 PM | 5:00 AM | same day |
| 5:00 PM | 7:00 AM | same day |
| 6:00 PM | 8:00 AM | same day |
| 9:00 PM | 11:00 AM | same day |
Why people convert UTC to HST time
- Scheduling a call from UTC to HST: a 10:00 AM start in UTC lands at 12:00 AM in HST, so you can confirm the slot without doing the arithmetic yourself.
- Handling a -10h gap: UTC and HST 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 HST is 11:00 PM in UTC.
- Keeping family and friends in sync: knowing that 8:00 PM in UTC is 10:00 AM in HST makes it easy to avoid calling at 3 AM.
- Always state the zone abbreviation, not just the hour. "3:00 PM UTC" 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 UTC takes the early slot, the next week HST does.
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.
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 UTC and HST
With a -10h offset there is no overlap inside a normal 9 AM – 5 PM day. HST opens at 9:00 AM HST, which is 11:00 PM in UTC, so real-time calls need an early-morning or late-evening slot on one side.
Business hours overlap
UTC and HST have no shared working hours because of the -10h gap. Teams need to alternate early starts or rely on asynchronous handovers.
UTC is 10 hours behind HST (UTC UTC+00:00 → HST UTC-10:00). 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 UTC and HST?
UTC (UTC, UTC+00:00) is 10 hours behind HST (HST, UTC-10:00). The gap is currently -10h.
How do I convert UTC time to HST time?
Add -10h to UTC local time. For example, 9:00 AM in UTC is 11:00 PM in HST (previous day).
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 -10h offset from UTC.
What is the best time to call HST from UTC?
There is no shared working-hours window because of the -10h gap. The closest option is 1:00 PM in UTC, which is 3:00 AM in HST.
Which is behind, UTC or HST?
UTC is 10 hours behind HST. When it is 12:00 PM in UTC it is 2:00 AM in HST.
Does daylight saving time affect the UTC–HST difference?
Neither zone observes daylight saving time, so the -10h offset between UTC and HST is fixed all year.
Which other cities share UTC's time zone?
UTC also covers London, Dublin, Reykjavik, Accra, Lisbon, Dakar.
Which countries use UTC, UTC's zone?
UTC is used in Used worldwide as reference, Same zone as: UK, Ireland, Iceland, Portugal, Ghana.
Is there a day difference between UTC and HST?
Not normally. The -10h gap only pushes the date over the previous day.
What is the time difference between UTC and HST?
HST is -10h from UTC.
What timezone is UTC in?
UTC operates on its local timezone.
What timezone is HST in?
HST operates on its local timezone.
Which countries use UTC (Coordinated Universal Time)?
UTC is used in Used worldwide as reference, Same zone as: UK, Ireland, Iceland, Portugal, Ghana.
Does UTC observe daylight saving time?
No, UTC does not observe daylight saving time and remains at UTC+00:00 year-round.
What are some interesting facts about UTC?
UTC is the basis for all civil time zones worldwide. The abbreviation 'UTC' is a compromise between English (CUT) and French (TUC).
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 UTC, what time is it in HST?
When it is 12:00 AM (midnight) in UTC (UTC), it is -10h later in HST (HST).
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