Honolulu to Seoul
+19hHonolulu
HSTSOURCESeoul
KSTGreen rows indicate typical business hours (9 AM - 5 PM)
HST and KST on the World Map
The map below highlights the HST (Hawaii Standard Time) and KST (Korea Standard 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).
KST – Korea Standard Time
UTC+09:00Korea Standard Time (KST) is the time zone for South Korea, 9 hours ahead of UTC.
- •South Korea does not observe daylight saving time.
- •Seoul is home to Samsung, LG, and Hyundai headquarters.
- •KST is the same offset as JST (UTC+09:00).
About Honolulu
WikipediaHonolulu operates on Hawaii Standard Time (HST), UTC-10 with no daylight saving. Hawaii's consistent time makes it a predictable connection between Asia and mainland USA.
Pearl Harbor memorial receives over 2 million visitors annually.
About Seoul
WikipediaSeoul operates on Korea Standard Time (KST), UTC+9, same as Japan. As a global tech and entertainment hub, Seoul coordinates with East Asian markets.
Seoul has the fastest average internet speed in the world.
Honolulu vs Seoul: Offsets, DST and Best Call Times
Honolulu runs on Hawaii-Aleutian Standard Time (HST) at UTC-10:00. Seoul runs on Korean Standard Time (KST) at UTC+09:00. That puts Honolulu 19 hours ahead of Seoul — a difference of +19h at the current offsets.
In practice, when it is 9:00 AM in Honolulu it is 4:00 AM in Seoul on the next day. Midnight in Honolulu is 7:00 PM in Seoul. Neither zone observes daylight saving time, so the offset between them stays constant all year.
Honolulu to Seoul time conversion table
| Honolulu (HST) | Seoul (KST) | Day |
|---|---|---|
| 12:00 AM | 7:00 PM | same day |
| 6:00 AM | 1:00 AM | next day |
| 7:00 AM | 2:00 AM | next day |
| 8:00 AM | 3:00 AM | next day |
| 9:00 AM | 4:00 AM | next day |
| 12:00 PM | 7:00 AM | next day |
| 3:00 PM | 10:00 AM | next day |
| 5:00 PM | 12:00 PM | next day |
| 6:00 PM | 1:00 PM | next day |
| 9:00 PM | 4:00 PM | next day |
Why people convert Honolulu to Seoul time
- Scheduling a call from Honolulu to Seoul: a 10:00 AM start in Honolulu lands at 5:00 AM in Seoul the next day, so you can confirm the slot without doing the arithmetic yourself.
- Handling a +19h gap: Honolulu and Seoul 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 Seoul is 4:00 AM in Honolulu.
- Keeping family and friends in sync: knowing that 8:00 PM in Honolulu is 3:00 PM in Seoul 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 +19h gap is not.
- With a +19h gap there is no shared 9-to-5 window, so alternate the early start: one week Honolulu takes the early slot, the next week Seoul 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 KST (Korea Standard Time)
Korea Standard Time (KST) is the time zone used in South Korea. It shares the same UTC offset as Japan Standard Time but is a distinct time zone. South Korea does not observe daylight saving time. Seoul, the capital, is a major global tech and business hub.
Best time to call between Honolulu and Seoul
With a +19h offset there is no overlap inside a normal 9 AM – 5 PM day. Seoul opens at 9:00 AM KST, which is 4:00 AM in Honolulu, so real-time calls need an early-morning or late-evening slot on one side.
Business hours overlap
Honolulu and Seoul have no shared working hours because of the +19h gap. Teams need to alternate early starts or rely on asynchronous handovers.
Honolulu is 19 hours ahead of Seoul (HST UTC-10:00 → KST UTC+09:00). 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 Honolulu and Seoul?
Honolulu (HST, UTC-10:00) is 19 hours ahead of Seoul (KST, UTC+09:00). The gap is currently +19h.
How do I convert Honolulu time to Seoul time?
Add +19h to Honolulu local time. For example, 9:00 AM in Honolulu is 4:00 AM in Seoul (next day).
What time is it in Seoul right now?
Seoul uses KST at UTC+09:00. Use the live converter at the top of this page — it updates in real time and already accounts for the +19h offset from Honolulu.
What is the best time to call Seoul from Honolulu?
There is no shared working-hours window because of the +19h gap. The closest option is 1:00 PM in Honolulu, which is 8:00 AM in Seoul.
Which is ahead, Honolulu or Seoul?
Honolulu is 19 hours ahead of Seoul. When it is 12:00 PM in Honolulu it is 7:00 AM in Seoul.
Do Honolulu and Seoul use different time zones?
Honolulu (USA) uses HST at UTC-10:00, while Seoul (South Korea) uses KST at UTC+09:00. The IANA identifiers are Pacific/Honolulu and Asia/Seoul.
Does daylight saving time affect the Honolulu–Seoul difference?
Neither zone observes daylight saving time, so the +19h offset between Honolulu and Seoul is fixed all year.
Which other cities share Honolulu's time zone?
HST also covers Honolulu, Hilo, Kailua, Pearl City, Kapolei.
Which countries use HST, Honolulu's zone?
HST is used in United States (Hawaii).
Is there a day difference between Honolulu and Seoul?
Sometimes. The +19h gap is large enough that 8:00 PM or later in Honolulu already falls on the next day in Seoul.
What is the time difference between Honolulu and Seoul?
Seoul is +19h from Honolulu.
What timezone is Honolulu in?
Honolulu operates on Hawaii Standard Time (HST), UTC-10 with no daylight saving. Hawaii's consistent time makes it a predictable connection between Asia and mainland USA.
What timezone is Seoul in?
Seoul operates on Korea Standard Time (KST), UTC+9, same as Japan. As a global tech and entertainment hub, Seoul coordinates with East Asian markets.
What are the business hours in Honolulu?
Standard business hours in Honolulu are 8:00 AM - 5:00 PM HST.
What are the business hours in Seoul?
Standard business hours in Seoul are 9:00 AM - 6:00 PM KST.
What is the best time to schedule a call between Honolulu and Seoul?
The best overlap for a call is when both cities are in business hours. Honolulu works 8:00 AM - 5:00 PM HST and Seoul works 9:00 AM - 6:00 PM KST (+19h difference). Try scheduling during the overlapping window for maximum convenience.
What currencies are used in Honolulu and Seoul?
Honolulu uses USD ($) while Seoul uses KRW (₩). Check current exchange rates when planning travel or business between these cities.
How do Honolulu and Seoul compare in size?
Honolulu has a population of approximately 350,000 (metro: 1 million), while Seoul has approximately 9.7 million (metro: 25.5 million).
What are the major landmarks in Honolulu and Seoul?
Honolulu is known for Waikiki Beach, Diamond Head, Pearl Harbor. Seoul is famous for Gyeongbokgung Palace, N Seoul Tower, Bukchon Hanok Village.
Do Honolulu and Seoul have stock exchanges?
Yes. Honolulu has the N/A (Uses NYSE/NASDAQ) and Seoul has the KRX (Korea Exchange). The +19h time difference affects trading hour overlaps between these exchanges.
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 KST timezone?
Major cities in the KST timezone include Seoul, Busan, Incheon, Daegu, Daejeon, Pyongyang.
What is the UTC offset for KST?
Korea Standard Time (KST) is at UTC+09:00.
What should I know about the KST timezone?
South Korea does not observe daylight saving time. Seoul is home to Samsung, LG, and Hyundai headquarters.
When is it midnight in Honolulu, what time is it in Seoul?
When it is 12:00 AM (midnight) in Honolulu (HST), it is +19h later in Seoul (KST).
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