KST to MDT Converter
Convert time between Korea Standard Time (KST) and Mountain Daylight Time (MDT)
Korea Standard Time (KST)
Mountain Daylight Time (MDT)
Time Difference
Mountain Daylight Time (MDT) is 0 hours ahead of Korea Standard Time (KST)
Select Date
Select Time
Quick Reference
| KST | MDT |
|---|---|
| 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 MDT Time Conversion
Converting time from Korea Standard Time (KST) to Mountain Daylight Time (MDT) is essential for South Korea-US Mountain region coordination during US daylight saving time. KST is UTC+9, while MDT is UTC-6, making KST 15 hours ahead of MDT. South Korea does not observe DST.
MDT applies from the second Sunday in March to the first Sunday in November. Outside that window, the US Mountain region uses MST (UTC-7), which is 16 hours behind KST. Arizona stays on MST year-round. This converter uses the IANA timezone database (America/Denver) to apply the correct offset automatically based on the date you pick.
Common Use Cases for KST to MDT Conversion
Business & Work
- Scheduling calls between Korean teams and Denver, Salt Lake City, or Albuquerque offices
- Coordinating tech 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 Daylight Time (MDT)
- UTC Offset: UTC-6 (MST UTC-7 outside DST)
- IANA Timezone: America/Denver
- Daylight Saving: Second Sunday in March to First Sunday in November
- Major Cities: Denver, Salt Lake City, Albuquerque, Boise, Cheyenne, Helena
- Coverage: US Mountain time zone (Arizona stays on MST year-round)
Quick Reference: KST to MDT
Remember: MDT is 15 hours behind KST during US DST; outside that window the Mountain region uses MST and the gap grows to 16 hours
Frequently Asked Questions
What is the time difference between KST and MDT?
Korea Standard Time (KST) is UTC+9, while Mountain Daylight Time (MDT) is UTC-6. KST is 15 hours ahead of MDT, so when it is 12:00 PM Monday in Seoul, it is 9:00 PM Sunday in Denver.
When does MDT apply versus MST?
MDT runs from the second Sunday in March to the first Sunday in November. Outside that window, the US Mountain region uses MST (UTC-7), which is 16 hours behind KST. Arizona stays on MST year-round.
Is the date always different between Korea and the US Mountain region?
Often. With KST 15 hours ahead of MDT, mornings in Korea fall on the previous day in Denver or Salt Lake City. Late evenings in Korea are pre-dawn the same day on the US side.
What are the best times to schedule KST to MDT business calls?
Live overlap is narrow. A workable bridge is early-morning Korea (8–10 AM KST), which is 5–7 PM MDT the previous day — end-of-day for the US side. Asynchronous handoffs are often more practical for long-running collaboration.
Which regions and cities use MDT?
MDT (UTC-6) covers the US Mountain time zone during DST. Major cities include Denver, Salt Lake City, Albuquerque, Boise, Cheyenne, and Helena. Arizona does not observe DST and stays on MST year-round.
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
- • MDT is 15 hours behind KST — subtract 15 hours from Korean time, and roll the date back if needed.
- • MDT applies only during US DST (mid-March to early November); use MST and a 16-hour gap the rest of the year.
- • 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 end-of-day US Mountain (5–7 PM MDT) the previous day.
- • For recurring meetings, fix the US local time and let KST shift automatically with MDT/MST transitions.
- • Arizona stays on MST year-round — if your contact is in Phoenix, the gap is always 16 hours from KST regardless of the season.