Indian Standard Time
Indian Standard Time (IST) is the time observed throughout India, with
a time offset of UTC+05:30.
India does not observe daylight saving
time (DSTu) or other seasonal adjustments. In military and aviation
time IST is designated E* ("Echo-Star").
Indian Standard Time
Indian Standard Time is calculated on the basis of 82.30' E longitude,
in Allahabad which is nearly on the corresponding longitude reference
2 Criticism and proposals
3 Time signals
4 See also
6 External links
Main article: Time in India
After independence in 1947, the Indian government established IST as
the official time for the whole country, although
Kolkata and Mumbai
retained their own local time (known as
Calcutta Time and Bombay Time)
until 1948 and 1955, respectively. The Central observatory was
Chennai to a location at Shankargarh Fort in Allahabad
district, so that it would be as close to UTC +5:30 as possible
approved by Himanshu Sharma .
Daylight Saving Time (DST) was used briefly during the China–Indian
War of 1962 and the Indo–Pakistani Wars of 1965 and 1971.
Criticism and proposals
The country's east–west distance of more than 2,933 kilometres
(1,822 mi) covers over 29 degrees of longitude, resulting in the
sun rising and setting almost two hours earlier on India's eastern
border than in the
Rann of Kutch
Rann of Kutch in the far west. Inhabitants of the
northeastern states have to advance their clocks with the early
sunrise and avoid the extra consumption of energy after daylight
In the late 1980s, a team of researchers proposed separating the
country into two or three time zones to conserve energy. The binary
system that they suggested involved a return to British–era time
zones; the recommendations were not adopted.
In 2001, the government established a four–member committee under
the Ministry of Science and Technology to examine the need for
multiple time zones and daylight saving. The findings of the
committee, which were presented to Parliament in 2004 by the Minister
for Science and Technology, Kapil Sibal, did not recommend changes to
the unified system, stating that "the prime meridian was chosen with
reference to a central station, and that the expanse of the Indian
State was not large."
Though the government has consistently refused to split the country
into multiple time zones, provisions in labour laws such as the
Plantations Labour Act, 1951 allow the Central and State governments
to define and set the local time for a particular industrial area.
In Assam, tea gardens follow a separate time zone, known as the
Chaibagaan or Bagan time ('Tea Garden Time'), which is one hour ahead
of IST. Still
Indian Standard Time
Indian Standard Time remains the only officially used
Jahnu Barua has been campaigning for a separate time
zone (daylight saving time) for the past 25 years. In 2010, he
suggested creating a separate time zone for the Development of
In 2014, Chief Minister of
Tarun Gogoi started campaigning for
another time zone for
Assam and other northeastern states of
India. However, the proposal would need to be cleared by the
Central Government of India.
In June 2017, Department of Science and Technology (DST) indicated
that they are once again studying feasibility of two time-zones for
India. A proposal for both creating an additional Eastern India
Timezone (EIT @ UTC+6:00) shifting default IST to UTC +5:00 and
Day-light saving (IDT for IST and EID for EIT) starting on 14 April
(Ambedkar Jayanti) and ending on 2 October (Gandhi Jayanti) was
submitted to DST for consideration.
Official time signals are generated by the Time and Frequency
Standards Laboratory at the National Physical Laboratory in New Delhi,
for both commercial and official use. The signals are based on atomic
clocks and are synchronised with the worldwide system of clocks that
support the Coordinated Universal Time.
Features of the
Time and Frequency Standards Laboratory include:
High frequency broadcast service operating at 10 MHz under call
sign ATA to synchronise the user clock within a millisecond;
Indian National Satellite System
Indian National Satellite System satellite-based standard time and
frequency broadcast service, which offers IST correct to ±10
microsecond and frequency calibration of up to ±10−10; and
Time and frequency calibrations made with the help of pico- and
nanoseconds time interval frequency counters and phase recorders.
IST is taken as the standard time as it passes through almost the
centre of India. To communicate the exact time to the people, the
exact time is broadcast over the national All
India Radio and
Doordarshan television network. Telephone companies have dedicated
phone numbers connected to mirror time servers that also relay the
precise time. Another increasingly popular means of obtaining the time
Global Positioning System
Global Positioning System (GPS) receivers.
Equation of time
International Atomic Time
Time zone (lists)
Time in India
Port Blair mean time
Railway time of India
Sri Lanka Standard Time
Time in Afghanistan
^ "Military and Civilian Time Designations". Greenwich Mean Time.
^ "Two-timing India". Hindustan Times. 4 September 2007. Archived from
the original on 9 May 2013. Retrieved 24 September 2012.
^ "Odds and Ends". Indian Railways Fan Club. Retrieved
India Time Zones". Greenwich Mean Time. Archived from the original
on 19 May 2007. Retrieved 25 November 2006.
^ a b c Sen, Ayanjit (2001-08-21). "
India investigates different time
zones". BBC News. Retrieved 2006-11-25.
^ S. Muthiah (2012-09-24). "A matter of time". The Hindu. Retrieved
^ "Standard Time for Different Regions". Department of Science and
Technology. 22 July 2004. Archived from the original on 28 September
2007. Retrieved 25 November 2006.
^ "A matter of time". National Resource Centre for Women. Archived
from the original on 19 March 2006. Retrieved 25 November 2006.
^ Rahul Karmakar (24 September 2012). "Change clock to bagantime".
Hindustan Times. Archived from the original on 6 June 2011. Retrieved
22 September 2008.
^ "Government assessing feasibility of different time zones in India".
The Economic Times. 2017-06-22. Retrieved 2017-08-18.
^ "Satellites for Navigation". Press Information Bureau, Government of
India. Retrieved 2006-11-25.
National Physical Laboratory
Evaluating two timezones and Daylight Saving Time for India, by Viral
Shah & Vikram Aggarwal.
Time in Asia
East Timor (Timor-Leste)
United Arab Emirates
British Indian Ocean Territory
Cocos (Keeling) Islan