What is the standard time zone used in Seoul, South Korea?

The standard time zone used in Seoul, South Korea, is Korea Standard Time (KST).

KST is set at UTC+09:00, so Seoul is nine hours ahead of Coordinated Universal Time. South Korea currently uses this offset throughout the year and does not observe daylight saving time. That makes KST a particularly stable answer: unlike Paris, Seoul does not normally switch to a summer clock.

Korea’s modern time-zone history includes several changes. The Korean Empire adopted GMT+08:30 in 1908, but the Japanese colonial administration shifted the country to GMT+09:00 in 1912. South Korea briefly returned to GMT+08:30 in 1954, then restored GMT+09:00 in 1961. Daylight saving time was temporarily used during the 1988 Seoul Olympics, from May 8 to October 9, to improve international broadcast timing.

The main mix-up is Japan Standard Time: both Japan and South Korea currently use UTC+09:00, but Seoul’s official zone name is Korea Standard Time. The IANA identifier for South Korea is Asia/Seoul.