Time Zone History

South Korea time zone history

The record holds 5 different UTC offsets, tied for the most among the 9 zones on UTC+9 standard time. Daylight saving time was used in 2 years since 1970, last in 1988; under the current rules the clocks no longer change.

UTC+9

Standard time is UTC+9 (KST) all year under the current rules.

tz database name Asia/Seoul

Convert a time from South Korea

Summer time in 2 of 57 years since 1970

UTC+8:27:52, UTC+8:30: behind today’s standard timeUTC+9: today’s standard timeUTC+9:30: 30 minutes ahead of today’s standard timeUTC+10: 1 hour ahead of today’s standard timeUTC+8:27:52, UTC+8:30: behindtoday’s standard timeUTC+9: today’s standard timeUTC+9:30: 30 minutes ahead oftoday’s standard timeUTC+10: 1 hour ahead of today’sstandard time

How to read this chart

Before 1970

190019201940196019001940
JanFebMarAprMayJunJulAugSepOctNovDec1970198019902000201020202028JFMAMJJASOND1970198019902000201020202028

Standard time changes

DateChangeNew standard timeClock label
Before 1970
April 1, 1908Local mean time (UTC+8:27:52) replacedUTC+8:30KST
January 1, 1912Standard time forward 30 minutesUTC+9JST
March 21, 1954Standard time back 30 minutesUTC+8:30KST
August 10, 1961Standard time forward 30 minutesUTC+9KST

Daylight saving periods

YearsClocks go forwardClocks go backShift and labels
Before 1970
1948June 1September 131 hour, KST to KDT
1949April 3September 111 hour, KST to KDT
1950April 1September 101 hour, KST to KDT
1951May 6September 91 hour, KST to KDT
1955May 5September 91 hour, KST to KDT
1956May 20September 301 hour, KST to KDT
1957May 5September 221 hour, KST to KDT
1958–1960first Sunday in May, 00:00third Sunday in September, 00:001 hour, KST to KDT
Since 1970
1987–1988second Sunday in May, 02:00second Sunday in October, 03:001 hour, KST to KDT

Also on UTC+9

North Korea, Japan, Chita (Russia), Yakutsk (Russia), Khandyga (Russia), Palau, Jayapura (Indonesia) and East Timor.

Clocks next door since 1970

  • North Korea (195 km): same time except 1,302 days in 1987, 1988 and 2015–2018.
  • Vladivostok (Russia) (753 km): usually 1 hour ahead; different on 6,933 days in 1981–2014.
  • Shanghai (China) (864 km): usually 1 hour behind; different on 700 days in 1986–1991.
  • Japan (1,159 km): same time except 308 days in 1987 and 1988.
  • Taiwan (1,483 km): usually 1 hour behind; different on 766 days in 1974, 1975, 1979, 1987 and 1988.

How it compares

Standard time has stayed at UTC+9 since 1961.

On standard time, clocks in Seoul run 32 minutes ahead of local mean solar time.