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Time in Indonesia
The Indonesian archipelago geographically stretches across four time zones from UTC+06:00 in Aceh to UTC+09:00 in Papua. However, the Indonesian government recognizes only three time zones in its territory:
- Western Indonesia Time (WIB) — seven hours ahead (UTC+07:00) of the Coordinated Universal Time (UTC or GMT)
- Central Indonesia Time (WITA) — eight hours ahead (UTC+08:00) of UTC; and
- 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 and Bali through the provincial boundaries of West and Central Kalimantan. The border between the Central and Eastern time zones runs north from the eastern tip of Indonesian Timor to the eastern tip of Sulawesi.
Daylight saving time is no longer observed anywhere in Indonesia.
In Indonesia, the keeping of standard time is divided into three time zones:
|Time zone name||Name in Indonesian||Current time and abbreviation||UTC offset||WIB offset||Area covered||Population|
|Western Indonesia Time||Waktu Indonesia Barat||17:00, 6 December 2021 WIB||UTC+07:00||WIB+/-0h||Sumatra (consists of Aceh, Bengkulu, Jambi, Lampung, North Sumatra, Riau, South Sumatra, and West Sumatra), Riau Islands, Bangka Belitung Islands, Java (consists of Banten, Jakarta, West Java, Central Java, Special Region of Yogyakarta, and East Java), West Kalimantan and Central Kalimantan||207,485,712|
|Central Indonesia Time||Waktu Indonesia Tengah||18:00, 6 December 2021 WITA||UTC+08:00||WIB+1h||South Kalimantan, East Kalimantan, North Kalimantan, Sulawesi (consists of North Sulawesi, Gorontalo Central Sulawesi, West Sulawesi, South Sulawesi and Southeast Sulawesi), Bali, West Nusa Tenggara and East Nusa Tenggara||40,840,394|
|Eastern Indonesia Time||Waktu Indonesia Timur||19:00, 6 December 2021 WIT||UTC+09:00||WIB+2h||Maluku, North Maluku, West Papua and Papua||6,855,338|
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).
Standardized Time Zone (Indonesia 1932)
- Northern Sumatra Time (NST) (UTC+06:30), was observed in Aceh, Padang and Medan.
- Central and Southern Sumatra Time (CSST) (UTC+07:00), was observed in Bengkulu, Palembang and Lampung.
- Java, Bali, and Borneo Time (JBBT) (UTC+07:30), was observed in Java, Bali, Madura and Kalimantan.
- Celebes Time (CBT) (UTC+08:00), was observed in Sulawesi and Lesser Sunda Islands.
- Moluccan Time (MCT) (UTC+08:30), was observed in Ternate, Namlea, Ambon and Banda.
- West Irian Time (WIT) (UTC+09:00) was observed in West Irian. It observed during 1 November 1932 to 31 August 1944.
- Dutch New Guinea Time (DGT) (UTC+09:30), was observed in West Irian during named Dutch New Guinea because Netherlands still hold West Irian. It observed from 1 September 1944 to 31 December 1963.
Western parts of Indonesia observed 30-minute daylight saving time 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 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 (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 1942–1945.
Proposal for a single time zone
|12 March 2012||Coordinating Minister for the Economy Hatta Rajasa is reported to have said: "According to research, with a single time zone the country could cut costs by trillions of rupiah,"|
|26 May 2012||The Jakarta Post reported on 26 May 2012 that a single time zone using UTC+08:00 may start on 28 October 2012.|
|30 July 2012||Reported on 30 July 2012 as still on the agenda|
|31 August 2012||Jakarta Globe reported on 31 August 2012 that a single time zone is now put on hold. The Indonesian Economic Development Committee (KP3EI) cited that they will need at least 3 months to communicate and plan for the change. Hence this could happen in 2013.|
|30 January 2013||A deputy minister said the idea has been abandoned after missed two target dates: 17 August (Independence day) and 28 October 2012 (Youth Pledge day)|
|9 September 2013||Then the minister said that it's not abandoned, only without any definite date|
IANA time zone database
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