Time in Indonesia

The Indonesian archipelago geographically stretches across four time zones from UTC+7 in Aceh to UTC+9 in Western Papua. However, the Indonesian government only recognizes three time zones in its territory:

  • Indonesia Western Standard Timeseven hours in advance (UTC+7) of Greenwich Mean Time (GMT)
  • Indonesia Central Standard Time eight hours ahead (UTC+8) of GMT; and
  • Indonesia Eastern Standard Timenine hours ahead (UTC+9) of GMT

The boundary between the western and central time zones established is a line running north between Java and Bali through the center of Kalimantan. The border between central and eastern time zones runs north from the eastern tip of Timor to the eastern tip of Sulawesi.

Daylight saving time is not currently observed in almost all of Indonesia due to its tropical location, resulting in those areas using their respective time zone all year long. The only unofficial exceptions are Muara Teweh and Maurainu, which unofficially use Indonesian Western Daylight Time.

Current usage

In Indonesia, the keeping of standard time is divided into three time zones:

Indonesia Western Standard Time

Indonesia Western Standard Time (IWST) (WIB, Indonesian: Waktu Indonesia Barat) (UTC+07:00) is observed in:

IANA time zone database identifiers are "Asia/Jakarta" and "Asia/Pontianak"

Indonesia Central Standard Time

Indonesia Central Standard Time (ICST) (WITA, Indonesian: Waktu Indonesia Tengah) (UTC+08:00) is observed in:

IANA time zone database identifier is "Asia/Makassar"

Indonesia Eastern Standard Time

Indonesia Eastern Standard Time (IEST) (WIT, Indonesian: Waktu Indonesia Timur) (UTC+09:00) is observed in:

IANA time zone database identifier is "Asia/Jayapura"

It observed since January 1, 1988 (based Keputusan Presiden No. 41 tahun 1987).[1] Before it, Western and Central Kalimantan used ICST, and Bali used IWST from January 1, 1964 (based Keputusan Presiden No. 243 tahun 1963)[2]

Historical usage

During the colonial era until early independence,[3] the time in Indonesia (Dutch East Indies) was regulated as follows:

Standardization 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 (Jawa), 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, Sofifi and Banda.
  • West Irian Time (WIT) (UTC+09:00) was observed in West Irian. It observed during November 1, 1932 to August 31, 1944.[4]
    • 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 September 1, 1944 to December 31, 1963.[4]

Daylight saving time was observed in Jakarta [5] from May 1, 1948 to May 1, 1950. It's UTC offset during daylight saving time is UTC+08:00.

It observed from November 1, 1932 to March 22, 1942, and from September 23, 1945 to December 31, 1963, except West Irian, ever observed it until 1944 and Jakarta, ever observed it all, except from May 1, 1948 to May 1, 1950.

From March 23, 1942 to September 22, 1945, All region in Indonesia, except West Irian used Japan Standard Time (JST) (UTC+09:00) for the sake of the effectiveness of Japanese military operations in Indonesia[5] This makes the western parts of Indonesia on double daylight saving time and central parts of Indonesia on daylight saving time.

Single time zone proposal

Date Event
2012-03-12Coordinating 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,” [6]
2012-05-26The Jakarta Post reported on 26 May 2012 that a single time zone using UTC+08:00 may start on Oct 28, 2012.[7]
2012-07-30Reported on 30 July 2012 as still on the agenda[8]
2012-08-31Jakarta Globe reported on 31 August 2012 that a single time zone is now put on hold.[9] 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.
2013-01-30A deputy minister said the idea has been abandoned after missed two target dates: 17 August (Independence day) and 28 October 2012 (Youth Pledge day) [10]
2013-02-09Then the minister said that it's not abandoned, only without any definite date [11]

IANA time zone database

The IANA time zone database contains four zones for Indonesia in the file zone.tab.

  • Asia/Jakarta
  • Asia/Pontianak
  • Asia/Makassar
  • Asia/Jayapura

See also


  1. Soeharto, Letnan Jendral (26 November 1987). "Keputusan Presiden No. 41 Tahun 1987" (PDF). Keputusan Presiden No. 41 tahun 1987 - BAPPENAS. BAPPENAS. Archived from the original (PDF) on 20 April 2016. Retrieved 9 April 2016.
  2. VIVA.co.id, PT. VIVA MEDIA BARU -. "Indonesia Pernah Ubah 9 Kali Zona Waktu". bisnis.news.viva.co.id. Retrieved 2016-04-09.
  3. http://www.timetableimages.com/ttimages/complete/ga63/ga63-2.jpg
  4. 1 2 "Time Zone in Jayapura, Papua, Indonesia". www.timeanddate.com. Retrieved 2016-04-09.
  5. 1 2 "Time Zone & Clock Changes in Jakarta, Jakarta Special Capital Region, Indonesia". www.timeanddate.com. Retrieved 30 March 2018.
  6. "Archived copy". Archived from the original on 20 May 2012. Retrieved 27 May 2012.
  7. Post, The Jakarta. "Single time zone may begin in late October". thejakartapost.com. Retrieved 30 March 2018.
  8. "Indonesia to implement single time zone". khabarsoutheastasia.com. Archived from the original on 31 July 2012. Retrieved 30 March 2018.
  9. "Archived copy". Archived from the original on 18 October 2012. Retrieved 25 October 2012.
  10. http://bisnis.news.viva.co.id/news/read/386333-penyatuan-zona-waktu-indonesia-batal
  11. Okezone. "Hatta : Penyatuan Zona Waktu Tidak Batal : Okezone Economy". okezone.com. Retrieved 30 March 2018.

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