KST to MST Converter
Convert time between Korea Standard Time (KST) and Mountain Standard Time (MST)
Korea Standard Time (KST)
Mountain Standard Time (MST)
Time Difference
Mountain Standard Time (MST) is 0 hours ahead of Korea Standard Time (KST)
Select Date
Select Time
Quick Reference
| KST | MST |
|---|---|
| 11:00 | 20:00 |
| 13:00 | 22:00 |
| 15:00 | 00:00 |
| 17:00 | 02:00 |
| 19:00 | 04:00 |
| 21:00 | 06:00 |
| 23:00 | 08:00 |
| 01:00 | 10:00 |
| 03:00 | 12:00 |
| 05:00 | 14:00 |
| 07:00 | 16:00 |
| 09:00 | 18:00 |
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 KST to MST Time Conversion
Converting time from Korea Standard Time (KST) to Mountain Standard Time (MST) is essential for South Korea-US Mountain region coordination during US winter. KST is UTC+9, while MST is UTC-7, making KST 16 hours ahead of MST. South Korea does not observe DST.
Most of the US Mountain region switches to MDT (UTC-6) from the second Sunday in March to the first Sunday in November, dropping the gap to 15 hours. Arizona stays on MST year-round. This converter uses the IANA timezone database (America/Denver) to apply the correct offset automatically; for Arizona, the data file uses Phoenix, but the offset is identical to MST winter time.
Common Use Cases for KST to MST Conversion
Business & Work
- Scheduling calls between Korean teams and Denver, Salt Lake City, or Phoenix offices
- Coordinating tech, mining, or energy projects between South Korea and the US Mountain region
- Planning end-of-day handoffs from Seoul into the start of a Mountain region workday
Personal & Travel
- Keeping in touch with family or friends in the US Mountain region
- Planning travel from South Korea to Denver, Salt Lake City, or Phoenix
- Scheduling virtual events that span Asia and the US
Time Zone Information
Korea Standard Time (KST)
- UTC Offset: UTC+9 (no DST observed)
- IANA Timezone: Asia/Seoul
- Daylight Saving: South Korea does not observe daylight saving time
- Major Cities: Seoul, Busan, Incheon, Daegu, Daejeon, Gwangju, Jeju
- Coverage: All of South Korea
Mountain Standard Time (MST)
- UTC Offset: UTC-7 (UTC-6 MDT during DST)
- IANA Timezone: America/Denver
- Daylight Saving: Second Sunday in March to First Sunday in November (Arizona stays on MST year-round)
- Major Cities: Denver, Phoenix, Salt Lake City, Albuquerque, Boise, Cheyenne
- Coverage: US Mountain time zone, including Colorado, Utah, Wyoming, Montana, New Mexico, parts of Idaho, and Arizona (year-round)
Quick Reference: KST to MST
Remember: MST is 16 hours behind KST during US winter; during MDT the gap drops to 15 hours. Arizona stays on MST year-round.
Frequently Asked Questions
What is the time difference between KST and MST?
Korea Standard Time (KST) is UTC+9, while Mountain Standard Time (MST) is UTC-7. KST is 16 hours ahead of MST, so when it is 12:00 PM Monday in Seoul, it is 8:00 PM Sunday in Denver.
When does MST apply versus MDT?
MST runs from the first Sunday in November to the second Sunday in March. Outside that window, most of the US Mountain region uses MDT (UTC-6), which is 15 hours behind KST. Arizona stays on MST year-round.
Is the date always different between Korea and the US Mountain region?
Often. With KST 16 hours ahead of MST, mornings in Korea fall on the previous day in Denver, Salt Lake City, or Phoenix. Late evenings in Korea are pre-dawn the same day on the US side.
What are the best times to schedule KST to MST business calls?
Live overlap is narrow. A workable bridge is early-morning Korea (8–10 AM KST), which is 4–6 PM MST the previous day — end-of-day for the US side. Asynchronous handoffs are often more practical.
Which regions and cities use MST?
MST (UTC-7) covers the US Mountain time zone during winter, plus Arizona year-round. Major cities include Denver, Salt Lake City, Albuquerque, Phoenix, Boise, and Cheyenne.
Which regions use KST?
KST (UTC+9) is used by all of South Korea. Major cities include Seoul, Busan, Incheon, Daegu, Daejeon, Gwangju, and Jeju. South Korea does not observe daylight saving time.
Pro Tips
- • MST is 16 hours behind KST — subtract 16 hours from Korean time, and roll the date back if needed.
- • MST applies during US winter (early November to mid-March); during MDT the gap drops to 15 hours.
- • Korea never observes DST, so all seasonal change is on the US side.
- • For live calls, early-morning Korea (8–10 AM KST) lines up with late-afternoon US Mountain (4–6 PM MST) the previous day.
- • Arizona stays on MST year-round — if your contact is in Phoenix, the gap is always 16 hours from KST.
- • For recurring meetings, fix the US local time and let KST shift automatically with MDT/MST transitions.