Myanmar did not have a standard time before the British colonial period. Each region kept its own local mean time, according to the Burmese calendar rules: sunrise, noon, sunset and midnight.[note 1] The day was divided into eight 3-hour segments called baho (ဗဟို), or sixty 24-minute segments called nayi (နာရီ). Although the calendar consists of time units down to the millisecond level, the popular usage never extended beyond baho and at most nayi measurements; a gong was struck every nayi while a drum (စည်) and a large bell (ခေါင်းလောင်း) were struck to mark every baho.[5]
Type
Time
Burmese name
Description
Day
1 o'clock
နံနက် တစ်ချက်တီး
midway between sunrise and midday
2 o'clock
နေ့ နှစ်ချက်တီး
noon (midday)
3 o'clock
နေ့ သုံးချက်တီး
midway between noon and sunset
4 o'clock
နေ့ လေးချက်တီး
sunset
Night
1 o'clock
ည တစ်ချက်တီး
midway between sunset and midnight
2 o'clock
ည နှစ်ချက်တီး
midnight
3 o'clock
ည သုံးချက်တီး
midway between midnight and sunrise
4 o'clock
နံနက် လေးချက်တီး
sunrise
Colonial period
The use of a common time began in British Burma in the late 19th century. The first confirmed mention of Rangoon Mean Time (RMT) at GMT+6:24:40[note 2] being in use was in 1892,[6] a year before the country's first time ball observatory[note 3] was opened in Rangoon (Yangon) on 1 October 1893.[7][8] However, the use of RMT as the common time, at least in some sectors, most probably started earlier. (The country's first rail service, between Rangoon and Prome (Pyay), began on 2 May 1877,[9] and the non-authoritative IANA time zone database says RMT was introduced in 1880.[10]) On 1 July 1905,[11][12] a new standard time called Burma Standard Time (BST) at GMT+6:30—set to the longitude 97° 30' E, and 5 minutes and 20 seconds ahead of RMT—was first adopted by the Railways and Telegraph administrations.[11][13] Although the rest of the country came to adopt BST, RMT continued to be used in the city of Rangoon at least to 1927.[note 4] By 1930, however, BST apparently had been adopted in Rangoon as well.[note 5]
The standard time was reverted to GMT+6:30 after the war.[14] It has remained ever since, even after the country's independence in 1948. The only change has been its name in English; the official English name has been changed to Myanmar Standard Time[1] presumably since 1989 when the country's name in English was changed from Burma to Myanmar.[15] The country does not observe a daylight saving time.[2]
Standard time for British Burma from at least 1892 to 30 June 1905. Continued to be used in Rangoon (Yangon) at least to 1927[16] perhaps until 1929.[17]
Burma Standard Time
1 July 1905 – 30 April 1942
UTC+6:30:00
First adopted by Railways and Telegraph offices in 1905.[11][13] The October 2021 IANA database says it was introduced in 1920[14] but does not provide a source.
^(Clancy 1906: 57): The Burmese calendar recognizes two types of day: astronomical and civil. The mean Burmese astronomical day is from midnight to midnight, and represents 1/30th of a synodic month or 23 hours, 37 minutes and 28.08 seconds. The civil day comprises two halves, the first half beginning at sunrise and the second half at sunset.
^The time offset of 6:24:40 was the time used by the official time signal station in Rangoon per (Kinns 2020: 545) and the Admiralty (Admiralty 1895: 27); it was confirmed by the US Naval Intelligence report (USNI 1928: 723). The IANA database (https://www.iana.org/time-zones, version 2021e, released on 2021-10-21) gives 6:24:47, citing a secondary source (Reed and Low, The Indian Year Book, 1936–37, pp. 27–28); to be sure, the maintainers of the database do state that "this file is by no means authoritative." The 6:24:47 figure of (Reed and Low) may have been a typographical error from the 6:24:37 time given in (Indian Railway Board 1906: 7) which states that "... in Burma 6 1/2 hours ahead of Greenwich and 5 minutes 23 [sic] seconds earlier than Rangoon time." The Railway Board's 6:24:37 is likely false as the Admiralty records from 1898 to 1922 all say the official Rangoon time (per Kinns 2020: 545) was 6:24:40.
^(Kinns 2020: 544): The British apparently were using a local pagoda (later came to be known as the Signal Pagoda) in Rangoon for signaling at least since 1855, three years after their annexation of Lower Burma; but "no supporting evidence of a Rangoon time signal has been found in notices prior to 1893."
^An April 1927 dispatch by the US Naval Intelligence (USNI 1928: 723) says that the whole country, except Rangoon, used the standard time, GMT+6:30, while the city of Rangoon still used Rangoon Mean Time, which was 5 minutes 20 seconds behind Burma Standard Time (or GMT+6:24:40).
^(Kinns 2020: 545): the UK Admiralty records show that the time ball at the Rangoon time signal station was dropped twice each day, once at GMT+17:30:00 for 00:00:00 BST (i.e. GMT+6:30:00) and also at GMT+17:35:20 for 00:00:00 RMT (i.e. GMT+6:24:40); it was only in 1930 that the time ball at Rangoon was dropped for the standard time (GMT+6:30:00).