How many hours is MST behind KST?
As abbreviations, KST is always 16 hours ahead of MST: MST is UTC−7 and KST is UTC+9. To convert, add 16 hours.
Check which label you actually need: MST (Mountain Time is on MDT today). A time written with an abbreviation that is not in use is usually meant as the local time, so convert between the places instead: right now KST is 15 hours ahead of MST.
When the MST to KST time difference changes
For most of the year KST is 15 hours ahead of MST. From 1 November to 31 December 2026, KST is 16 hours ahead of MST instead, because the two places change their clocks on different dates. Meetings booked by the usual gap land an hour off in those weeks.
| Dates | KST vs MST | Length |
|---|---|---|
| 8 March 2026 to 31 October 2026 | 15 hours ahead | 238 days |
| 1 November 2026 to 31 December 2026 | 16 hours ahead | 61 days |
| 1 January 2027 to 13 March 2027 | 16 hours ahead | 72 days |
| 14 March 2027 to 6 November 2027 | 15 hours ahead | 238 days |
| 7 November 2027 to 31 December 2027 | 16 hours ahead | 55 days |
Calling hours for MST and KST
- When KST is 15 hours ahead of MST: no shared 09:00 to 17:00 hours; try 17:00 in MST (08:00 in KST).
- When KST is 16 hours ahead of MST: no shared 09:00 to 17:00 hours; try 17:00 in MST (09:00 in KST).