Technical Specifications & Standards
Official chronometric properties, ISO standards, and international database registry identifiers for Korea Standard Time:
Daylight Saving Time (DST) Transitions
⬆️ Spring Forward (Clocks Advance)
None (South Korea discontinued Daylight Saving Time after the 1988 Seoul Olympics)
⬇️ Fall Back (Clocks Return)
None
Observing Jurisdictions & Subdivisions
2 Sovereign NationsSovereign nations, administrative subdivisions, and regional territories officially operating under KST:
Regional Subdivisions & Territory Details
Financial Markets & Trading Hours
Trading runs in lockstep with the Tokyo Stock Exchange; anchors semiconductor, battery, and automotive export trade.
Local Hours: 09:00 - 15:30 KST
UTC Window: 00:00 - 08:30 UTC
Major Cities in KST
Primary metropolitan centers and financial hubs observing this time zone:
Adoption History & Astronomical Facts
Year Established: 1908
The Korean Empire originally established standard time in 1908 using UTC+8:30 based on 127.5° East. It shifted to UTC+9:00 in 1912. In August 2015, North Korea broke away and reverted to 'Pyongyang Time' at UTC+8:30, but Chairman Kim Jong Un agreed to realign clocks with Seoul in May 2018 during inter-Korean talks.
South Korea used daylight saving time during 1987 and 1988 primarily so that prime-time television viewers across North America could watch the 1988 Seoul Olympic Games live during evening hours.
Frequently Asked Questions about KST
What does KST stand for?
KST stands for Korea Standard Time, nine hours ahead of Coordinated Universal Time (UTC+9).
Are Seoul and Tokyo in the same time zone?
Yes. Korea Standard Time and Japan Standard Time both operate at UTC+9; clocks in Seoul and Tokyo read the exact same minute and hour.
Does South Korea use Daylight Saving Time?
No. South Korea has not adjusted its clocks for daylight saving since the 1988 Summer Olympics.