HST to KST Converter
Convert time between Hawaii Standard Time (HST) and Korea Standard Time (KST)
Hawaii Standard Time (HST)
Korea Standard Time (KST)
Time Difference
Korea Standard Time (KST) is 0 hours ahead of Hawaii Standard Time (HST)
Select Date
Select Time
Quick Reference
| HST | KST |
|---|---|
| 16:00 | 11:00 |
| 18:00 | 13:00 |
| 20:00 | 15:00 |
| 22:00 | 17:00 |
| 00:00 | 19:00 |
| 02:00 | 21:00 |
| 04:00 | 23:00 |
| 06:00 | 01:00 |
| 08:00 | 03:00 |
| 10:00 | 05:00 |
| 12:00 | 07:00 |
| 14:00 | 09:00 |
Top 10 Most Common Time Zones
| Abbreviation | Full Name | UTC Offset | Typical Use |
|---|---|---|---|
| UTC | Coordinated Universal Time | UTC ±0 | Global reference standard (servers, logs, APIs) |
| EST / EDT | Eastern (US) Time | UTC −5 / −4 | New York, Toronto — North American business hub |
| CST / CDT | Central (US) Time | UTC −6 / −5 | Chicago, Dallas — US central business region |
| PST / PDT | Pacific (US) Time | UTC −8 / −7 | San Francisco, Los Angeles — tech industry standard |
| GMT / BST | Greenwich Mean / British Summer Time | UTC 0 / +1 | UK, used globally as a reference with UTC |
| CET / CEST | Central European (Summer) Time | UTC +1 / +2 | Paris, Berlin, Amsterdam — EU business core |
| IST | India Standard Time | UTC +5:30 | India — major IT & outsourcing region |
| CST | China Standard Time | UTC +8 | Beijing, Shanghai — East Asia business hub |
| JST | Japan Standard Time | UTC +9 | Tokyo — finance & tech hub |
| AEST / AEDT | Australian Eastern (Daylight) Time | UTC +10 / +11 | Sydney, Melbourne — APAC regional business |
Why Time Zone Abbreviations Are Ambiguous
Unlike standardized identifiers (like America/New_York or Europe/London from the IANA tz database), abbreviations such as "CST" or "IST" are not globally unique. They can refer to different time zones depending on context — country, region, or even time of year (due to daylight saving time).
Common Ambiguous Time Zone Abbreviations
| Abbrev. | Common Meaning(s) | UTC Offset | Region(s) |
|---|---|---|---|
| CST | Central Standard Time / China Standard Time / Cuba Standard Time | UTC−6 / UTC+8 / UTC−5 | North America, China, Cuba |
| IST | Indian Standard Time / Irish Standard Time / Israel Standard Time | UTC+5:30 / UTC+1 / UTC+2 | India, Ireland, Israel |
| AST | Atlantic Standard Time / Arabia Standard Time | UTC−4 / UTC+3 | Caribbean, Canada, Middle East |
| PST | Pacific Standard Time / Philippine Standard Time | UTC−8 / UTC+8 | North America, Philippines |
| EST | Eastern Standard Time (North America / Australia) | UTC−5 / UTC+10 | North America, Australia |
✅ Best Practice
To avoid ambiguity, always:
- Use IANA tz identifiers — e.g.,
America/New_Yorkinstead of "EST" - Specify UTC offset explicitly — e.g.,
UTC−5when abbreviations must be used - Include the full timezone name — e.g., "Eastern Standard Time (EST)" with UTC offset
About HST to KST Time Conversion
Converting time from Hawaii Standard Time (HST) to Korea Standard Time (KST) is essential for Hawaii to South Korea coordination. HST is UTC-10 while KST is UTC+9, making KST 19 hours ahead of HST. Neither Hawaii nor South Korea observe daylight saving time, so the 19-hour difference holds steady throughout the year.
This consistency makes the conversion straightforward but the absolute gap is wide — Korea is almost always on the next calendar day relative to Hawaii. Whether you are booking flights from Honolulu to Seoul, scheduling cross-Pacific calls, or coordinating with a Korean team, our IANA-based converter gives you precise results year-round.
Common Use Cases for HST to KST Conversion
Business & Work
- Scheduling calls between Hawaii teams and Seoul or Busan offices
- Coordinating logistics and supply chains across the Pacific
- Planning content release windows that respect Korean business hours
Personal & Travel
- Keeping in touch with family and friends in South Korea
- Planning travel from Hawaii to Seoul or Jeju
- Scheduling online gaming, streams, or virtual events with Korean audiences
Time Zone Information
Hawaii Standard Time (HST)
- UTC Offset: UTC-10
- IANA Timezone: Pacific/Honolulu
- Daylight Saving: None - HST is standard time year-round
- Major Cities: Honolulu, Hilo, Kailua, Pearl City, Kahului
- Coverage: All Hawaiian islands
Korea Standard Time (KST)
- UTC Offset: UTC+9
- IANA Timezone: Asia/Seoul
- Daylight Saving: None - KST is standard time year-round
- Major Cities: Seoul, Busan, Incheon, Daegu, Daejeon, Gwangju, Jeju
- Coverage: All of South Korea
Quick Reference: HST to KST
Remember: KST is always 19 hours ahead of HST year-round. Neither region observes daylight saving time.
Frequently Asked Questions
What is the time difference between HST and KST?
Hawaii Standard Time (HST) is UTC-10, while Korea Standard Time (KST) is UTC+9. KST is 19 hours ahead of HST, so when it is 9:00 AM Monday in Honolulu, it is 4:00 AM Tuesday in Seoul.
Does the HST to KST time difference change throughout the year?
No. Neither Hawaii nor South Korea observes daylight saving time, so HST stays at UTC-10 and KST stays at UTC+9 every day of the year. The 19-hour difference is constant.
Is the date always different between Hawaii and Korea?
Almost always. With KST 19 hours ahead of HST, Korea is typically a calendar day ahead of Hawaii. For example, late-evening Sunday in Honolulu is already Monday afternoon in Seoul.
What are the best times to schedule HST to KST business calls?
Live overlap is narrow. A practical bridge is early-morning Korea (8 AM KST), which corresponds to 1 PM the previous day in Hawaii — the tail end of a Hawaiian workday hitting the start of a Korean morning. For deeper overlap, alternate meeting hours week to week.
Which regions and cities use KST?
KST (UTC+9) is used by all of South Korea. Major cities include Seoul, Busan, Incheon, Daegu, Daejeon, Gwangju, and Jeju.
Which regions use HST?
HST (UTC-10) is used exclusively by the Hawaiian Islands. Hawaii does not observe daylight saving time, so HST is the same year-round.
Pro Tips
- • KST is always 19 hours ahead of HST — a quick rule is to subtract 5 hours and add a day (e.g. 3 PM HST → 10 AM KST next day).
- • Neither Hawaii nor Korea observes daylight saving time, so this conversion is one of the most stable in the world.
- • For recurring meetings, 8 AM KST is roughly 1 PM the previous day in Hawaii — a workable Pacific bridge.
- • Late-afternoon HST (3–6 PM) lines up with morning KST the next day, making it the easiest window for live calls.
- • Korean public holidays (Lunar New Year, Chuseok) shift business activity by several days — keep them in mind for cross-Pacific projects.
- • When booking flights between Hawaii and Korea, expect to lose roughly a calendar day on the westward leg.