The

Indonesian Archipelago The islands of Indonesia, also known as the Indonesian Archipelago ( id, Kepulauan Indonesia) or Nusantara, may refer either to the islands comprising the country of Indonesia or to the geographical groups which include its islands. History ...

geographically stretches across four time zones from UTC+06:00 in

Aceh Aceh ( ), officially the Aceh Province ( ace, Nanggroë Acèh; id, Provinsi Aceh) is the westernmost province of Indonesia. It is located on the northernmost of Sumatra island, with Banda Aceh being its capital and largest city. Granted a s ...

to UTC+09:00 in Papua. However, the

Indonesian government The term Government of Indonesia ( id, Pemerintah Indonesia) can have a number of different meanings. At its widest, it can refer collectively to the three traditional branches of government – the executive branch, legislative branch and ju ...

recognises only three time zones in its territory, namely: *Western Indonesia Time (WIB) — seven hours ahead ( UTC+07:00) of the

Coordinated Universal Time Coordinated Universal Time or UTC is the primary time standard by which the world regulates clocks and time. It is within about one second of mean solar time (such as UT1) at 0° longitude (at the IERS Reference Meridian as the currently used ...

(UTC); *Central Indonesia Time (WITA) — eight hours ahead ( UTC+08:00) of UTC; *Eastern Indonesia Time (WIT) — nine hours ahead ( UTC+09:00) of UTC. The boundary between the Western and Central time zones was established as a line running north between

Java Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's List ...

and

Bali Bali () is a province of Indonesia and the westernmost of the Lesser Sunda Islands. East of Java and west of Lombok, the province includes the island of Bali and a few smaller neighbouring islands, notably Nusa Penida, Nusa Lembongan, and Nu ...

through the provincial boundaries of West and Central

Kalimantan Kalimantan () is the Indonesian portion of the island of Borneo. It constitutes 73% of the island's area. The non-Indonesian parts of Borneo are Brunei and East Malaysia. In Indonesia, "Kalimantan" refers to the whole island of Borneo. In 2019, ...

. The border between the Central and Eastern time zones runs north from the eastern tip of Indonesian

Timor Timor is an island at the southern end of Maritime Southeast Asia, in the north of the Timor Sea. The island is East Timor–Indonesia border, divided between the sovereign states of East Timor on the eastern part and Indonesia on the western p ...

to the eastern tip of

Sulawesi Sulawesi (), also known as Celebes (), is an island in Indonesia. One of the four Greater Sunda Islands, and the world's eleventh-largest island, it is situated east of Borneo, west of the Maluku Islands, and south of Mindanao and the Sulu Ar ...

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 ...

(DST) is no longer observed anywhere in Indonesia.

Current usage

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...

, the keeping of standard time is divided into three time zones: These time zones were first observed on 1 January 1988 (according to Presidential Decree 41/1987). Prior to that date, West and Central Kalimantan used WITA, while Bali belonged to WIB (since 29 November 1963).

Historical usage

During the colonial era, the time zones in Indonesia (

Dutch East Indies The Dutch East Indies, also known as the Netherlands East Indies ( nl, Nederlands(ch)-Indië; ), was a Dutch colony consisting of what is now Indonesia. It was formed from the nationalised trading posts of the Dutch East India Company, which ...

) were regulated as follows:

Standardised Time Zone (Indonesia 1932)

Western parts of Indonesia observed 30 minute daylight saving time (DST) from 1 November 1932 to 23 March 1942, and from 23 September 1945 to 1 January 1964 (except from 1 May 1948 to 1 May 1950, which observed 1 hour daylight saving time instead). West and Central

Borneo Borneo (; id, Kalimantan) is the third-largest island in the world and the largest in Asia. At the geographic centre of Maritime Southeast Asia, in relation to major Indonesian islands, it is located north of Java, west of Sulawesi, and eas ...

also observed 1 hour DST from 1 January 1964 to 1 January 1988. Eastern Indonesia observed 30 minute DST from 1 September 1944 until 1 January 1964. Furthermore, 20 minute daylight saving time was observed in Java and Sumatra from 1 January 1924 to 1 November 1932. From 23 March 1942 to 23 September 1945, both western and central parts of Indonesia used

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 ...

(JST) ( UTC+09:00) for the sake of the effectiveness of Japanese military operations in Indonesia This meant that western parts of Indonesia observed 2 hour daylight saving time, and central parts of Indonesia observed 1 hour daylight saving time during the period of Japanese occupation 1942 to 1945.

Proposal for a single time zone

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 four zones for Indonesia in the file zone.tab. *Asia/Jakarta *Asia/Pontianak *Asia/Makassar *Asia/Jayapura

References

External links

Indonesian Standard Time
{{Asia topic, Time in Time in Southeast Asia