MST to KST

About Mountain Time

Mountain Time is UTC−7 as MST and UTC−6 as MDT, on the same transition dates as the rest of the United States. Arizona is the exception worth knowing: almost all of it stays on MST all year, so for the eight months the rest of the zone is on MDT, Phoenix keeps the same clock as Los Angeles rather than Denver.

Cities on this clock: Denver, Salt Lake City, Calgary, Edmonton.

About Korea Standard Time

Korea is a fixed UTC+9, the same clock as Japan. Daylight saving was last used for the 1988 Olympics and has not returned.

Cities on this clock: Tokyo, Osaka, Seoul.

How the difference is worked out

The gap between Mountain Time and Korea Standard Time is not one number. The two zones change their clocks on different dates, so for part of the year the difference is 15 hours and for the rest it is something else — the table above lists each stretch of 2026 with the date it starts and which country's clocks moved.

With both zones on their own standard time — daylight saving not in force anywhere — Korea Standard Time is 16 hours ahead of Mountain Time. That figure never changes; everything else on this page follows from it plus whichever clocks have moved.

Every figure here comes from the IANA time zone database via your browser's own Intl engine, using the zone ids America/Denver and Asia/Seoul. Nothing is looked up on a server and nothing about your visit is recorded.