South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia. It constitutes the southern half of the Korea, Korean Peninsula and borders North Korea along the Korean Demilitarized Zone, with the Yellow Sea to the west and t ...

has one time zone, Korea Standard Time ( UTC+9), which is abbreviated KST. South Korea currently does not observe

daylight saving time Daylight saving time (DST), also referred to as daylight savings time, daylight time (Daylight saving time in the United States, United States and Daylight saving time in Canada, Canada), or summer time (British Summer Time, United Kingdom, ...

. From May 8 to October 9 in 1988,

was tested to better accommodate the calendar of competitions held during the

1988 Summer Olympics The 1988 Summer Olympics (), officially the Games of the XXIV Olympiad () and officially branded as Seoul 1988 (), were an international multi-sport event held from 17 September to 2 October 1988 in Seoul, South Korea. 159 nations were represe ...

Seoul Seoul, officially Seoul Special Metropolitan City, is the capital city, capital and largest city of South Korea. The broader Seoul Metropolitan Area, encompassing Seoul, Gyeonggi Province and Incheon, emerged as the world's List of cities b ...

History

In 1434, inventor Jang Yeong-sil developed

Korea Korea is a peninsular region in East Asia consisting of the Korean Peninsula, Jeju Island, and smaller islands. Since the end of World War II in 1945, it has been politically Division of Korea, divided at or near the 38th parallel north, 3 ...

'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 of liquid can then be measured. Water clocks are some of ...

, which

King Sejong Sejong (; 15 May 1397 – 8 April 1450), commonly known as Sejong the Great (), was the fourth monarch of the Joseon, Joseon dynasty of Korea. He is regarded as the greatest ruler in Korean history, and is remembered as the inventor of Hangu ...

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 horology, horological device that tells the time of day (referred to as civil time in modern usage) when direct sunlight shines by the position of the Sun, apparent position of the Sun in the sky. In the narrowest sense of the ...

called the ''angbu ilgu'' (), which King Sejong had placed in public so anyone could use it. In 1908, the

Korean Empire The Korean Empire, officially the Empire of Korea or Imperial Korea, was a Korean monarchical state proclaimed in October 1897 by King Gojong of the Joseon dynasty. The empire lasted until the Japanese annexation of Korea in August 1910. Dur ...

adopted a

standard time Standard time is the synchronization of clocks within a geographical region to a single time standard, rather than a local mean time standard. Generally, standard time agrees with the local mean time at some meridian that passes through the r ...

, GMT+08:30. In 1912, during the

Japanese occupation of Korea From 1910 to 1945, Korea was ruled by the Empire of Japan under the name Chōsen (), the Japanese reading of "Joseon". Japan first took Korea into its sphere of influence during the late 1800s. Both Korea (Joseon) and Japan had been under polic ...

, the

Governor-General of Korea Governor-general (plural governors-general), or governor general (plural governors general), is the title of an official, most prominently associated with the British Empire. In the context of the governors-general and former British colonies, ...

changed standard time to GMT+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), also known by his art name Unam (), 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 Provisiona ...

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

Park Chung-hee Park Chung Hee (; ; November14, 1917October26, 1979) was a South Korean politician and army officer who served as the third president of South Korea from 1962 after he seized power in the May 16 coup of 1961 until Assassination of Park Chung ...

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

American television Television is one of the Mass media in the United States, major mass media outlets in the United States. In 2011, 96.7% of households owned television sets; about 114,200,000 American households owned at least one television set each in August ...

viewers, South Korea observed

(GMT+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 peak time, is the block of broadcast programming taking place during the middle of the evening for television shows. It is mostly targeted towards adults (and sometimes families). It is used by the major television networks to ...

on the U.S. east coast.

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 borders China and Russia to the north at the Yalu River, Yalu (Amnok) an ...

also uses Korea Standard Time. From August 2015 to May 2018, North Korea changed its time zone to GMT+08:30, a time zone known as Pyongyang Standard Time, 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 and rules for observing daylight saving time, primarily intended for use with computer programs and operating systems. Paul Eggert has been its editor an ...

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

References

{{South Korea topics Geography of South Korea