South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korea, Korean Peninsula and sharing a Korean Demilitarized Zone, land border with North Korea. Its western border is formed ...

has one time zone, Korea Standard Time ( UTC+09:00), which is abbreviated KST. South Korea currently does not observe

daylight saving time Daylight saving time (DST), also referred to as daylight savings time or simply daylight time (United States, Canada, and Australia), and summer time (United Kingdom, European Union, and others), is the practice of advancing clocks (typicall ...

, but experimented with it during the

1988 Summer Olympics The 1988 Summer Olympics (), officially known as the Games of the XXIV Olympiad () and commonly known as Seoul 1988 ( ko, 서울 1988, Seoul Cheon gubaek palsip-pal), was an international multi-sport event held from 17 September to 2 October ...

Seoul Seoul (; ; ), officially known as the Seoul Special City, is the capital and largest metropolis of South Korea.Before 1972, Seoul was the ''de jure'' capital of the Democratic People's Republic of Korea (North Korea) as stated iArticle 103 ...

History

In 1434, inventor

Jang Yeong-sil Jang Yeong-sil (; ; 1390 – after 1442) was a Korean mechanical engineer, scientist, and inventor during the Joseon Dynasty (1392–1897). Although Jang was born as a peasant, King Sejong allowed Jang to work at the royal palace. Jang's inven ...

developed

Korea Korea ( ko, 한국, or , ) is a peninsular region in East Asia. Since 1945, it has been divided at or near the 38th parallel, with North Korea (Democratic People's Republic of Korea) comprising its northern half and South Korea (Republic o ...

's first automatic

water clock A water clock or clepsydra (; ; ) is a timepiece by which time is measured by the regulated flow of liquid into (inflow type) or out from (outflow type) a vessel, and where the amount is then measured. Water clocks are one of the oldest time- ...

, which

King Sejong Sejong of Joseon (15 May 1397 – 8 April 1450), personal name Yi Do (Korean: 이도; Hanja: 李祹), widely known as Sejong the Great (Korean: 세종대왕; Hanja: 世宗大王), was the fourth ruler of the Joseon dynasty of Korea. Initial ...

adapted as Korea's standard timekeeper. It is likely that Koreans used water clocks to keep time prior to this invention, but no concrete records of them exist. In 1437, Jang Yeong-sil, with Jeong Cho, created a bowl-shaped

sundial A sundial is a horological device that tells the time of day (referred to as civil time in modern usage) when direct sunlight shines by the apparent position of the Sun in the sky. In the narrowest sense of the word, it consists of a flat ...

called the ''angbu ilgu'' (

Hangul The Korean alphabet, known as Hangul, . Hangul may also be written as following South Korea's standard Romanization. ( ) in South Korea and Chosŏn'gŭl in North Korea, is the modern official writing system for the Korean language. The let ...

: 앙부일구), which King Sejong had placed in public so anyone could use it. Geographically, the western parts of

, including the

n capital city,

, are UTC+08:00. In 1908, the

Korean Empire The Korean Empire () was a Korean monarchical state proclaimed in October 1897 by Emperor Gojong of the Joseon dynasty. The empire stood until Japan's annexation of Korea in August 1910. During the Korean Empire, Emperor Gojong oversaw the Gwa ...

adopted a standard time that was hours ahead of

GMT Greenwich Mean Time (GMT) is the mean solar time at the Royal Observatory in Greenwich, London, counted from midnight. At different times in the past, it has been calculated in different ways, including being calculated from noon; as a cons ...

, UTC+08:30. In 1912, during the Japanese occupation of Korea, the

Governor-General of Korea Governor-general (plural ''governors-general''), or governor general (plural ''governors general''), is the title of an office-holder. In the context of governors-general and former British colonies, governors-general are appointed as viceroy t ...

changed standard time to UTC+09:00 to align with

Japan Standard Time , or , is the standard time zone in Japan, 9 hours ahead of UTC ( UTC+09:00). Japan does not observe daylight saving time, though its introduction has been debated on several occasions. During World War II, the time zone was often referred to a ...

. However, in 1954, the South Korean government under President

Syngman Rhee Syngman Rhee (, ; 26 March 1875 – 19 July 1965) was a South Korean politician who served as the first president of South Korea from 1948 to 1960. Rhee was also the first and last president of the Provisional Government of the Republic of Ko ...

reverted the standard time to UTC+08:30. Then in 1961, under the military government of President

Park Chung-hee Park Chung-hee (, ; 14 November 1917 – 26 October 1979) was a South Korean politician and army general who served as the dictator of South Korea from 1961 until his assassination in 1979; ruling as an unelected military strongman from 1961 ...

, the standard time was changed back to UTC+09:00 once again. In order to accommodate

American television Television is one of the major mass media outlets in the United States. , household ownership of television sets in the country is 96.7%, with approximately 114,200,000 American households owning at least one television set as of August 2013. ...

viewers, South Korea observed

( UTC+10:00) when Seoul hosted the

. The one-hour time change meant that many daytime events could be broadcast live from South Korea when it was

prime time Prime time or the peak time is the block of broadcast programming taking place during the middle of the evening for a television show. It is mostly targeted towards adults (and sometimes families). It is used by the major television networks to ...

on the

U.S. east coast The East Coast of the United States, also known as the Eastern Seaboard, the Atlantic Coast, and the Atlantic Seaboard, is the coastline along which the Eastern United States meets the Atlantic Ocean, North Atlantic Ocean. The eastern seaboard ...

North Korea North Korea, officially the Democratic People's Republic of Korea (DPRK), is a country in East Asia. It constitutes the northern half of the Korea, Korean Peninsula and shares borders with China and Russia to the north, at the Yalu River, Y ...

also uses Korea Standard Time. From August 2015 to May 2018, North Korea changed its time zone to UTC+08:30, a time zone known as

Pyongyang Standard Time Time in North Korea, called Pyongyang Time ( or PYT) or Standard Time of the Democratic People's Republic of Korea (), is since May 2018 equal to Korea Standard Time: 9 hours ahead of UTC ( UTC+09:00). Like South Korea, North Korea does not curren ...

, but the change was reverted to promote Korean unity.

IANA time zone database

The

IANA time zone database The tz database is a collaborative compilation of information about the world's time zones, primarily intended for use with computer programs and operating systems. Paul Eggert is its current editor and maintainer, with the organizational backi ...

contains one zone for South Korea in the file zone.tab, named Asia/Seoul.

References

{{South Korea topics