How Indian Standard Time was introduced in India on September 1, 1947 - Explained

Indian Standard Time (IST) was adopted as the official time zone for India on September 1, 1947, by the Indian Government. Jagran Josh explains how Indian Standard Time was introduced in India.

Created On: Sep 1, 2021 16:30 ISTModified On: Sep 1, 2021 18:29 IST
Clock Tower, Source: PTI
Clock Tower, Source: PTI

Indian Standard Time (IST) was adopted as the official time zone for India on September 1, 1947, by the Indian Government. IST is the time zone observed across the whole country with a time offset of UTC+5.30. During the British Raj in 1884, India used to have two time zones, Bombay time and Calcutta time. Dating back to the 4th century CE, the book ‘Surya Siddhanta’ states that India referred to the beginning of a 24-hour day with the sunrise at the prime meridian passing through Ujjain.

The ancient Indian astronomy divided the time measured from the onset of the sunrise into smaller time units equalling one prana (time span of one breath which is 4 seconds). 15 breaths equaled a minute. However, throughout the history of India, there was no standardized time zone.

Most of the towns and cities in India followed their local time reference until the railway system was introduced in the 1850s which gave rise to a significant need for a unified time zone. The British Raj marked the use of the current time zone in 1802. Today, Indian Standard Time (IST) is the only time zone followed in India. IST is ahead of Greenwich Mean Time (GMT) by 5.30 hours.  

Jagran Josh explains how Indian Standard Time was introduced in India on September 1, 1947.

What is Indian standard time?

Indian Standard Time (IST) is the official time zone of India. IST is computed on the basis of 82.5 degrees East longitude which passes through Mirzapur near Allahabad in Uttar Pradesh. The difference of longitude between Mirzapur in India and the Royal Observatory in Greenwich in London equals a time difference of 5 hours and 30 minutes. IST ahead of Greenwich Mean Time (GMT) by UTC+5.30.

The Greenwich Mean Time (GMT) is the mean solar time that the Royal Observatory in Greenwich measures at the midnight. GMT is synchronous with Universal Time Coordinate.

When was the Indian Standard Time officially introduced?

The Indian Standard Time (IST) was introduced in India on September 1, 1947, by the Indian Government of Independent India.

Who invented Indian Standard Time?

Dating back to the 4th century CE, the book ‘Surya Siddhanta’ states that India referred to the beginning of a 24-hour day with the sunrise at the prime meridian passing through Ujjain. That was further divided into smaller time units equalling to one prana (one breath which is 4 seconds). 15 breaths equaled one minute.

In 1792, the Madras Observatory in Chennai (then Madras) was set up by the British East India Company. In 1802, the first official astronomer of the Company, John Goldingham, computed the longitude of Madras as 5 hours and 30 minutes ahead of the Greenwich Mean Time (GMT). This became the first use of a local standard time which is later evolved into the current Indian Standard Time zone.

Why was Indian Standard Time adopted?

Throughout the history of India, there was no standardized time zone. Most of the towns and cities in India followed their local time reference.

In the 1850s, with the establishment of the railway system, the need for a unified time zone became more significant. But the British did not adopt the standard time until 1905.

When in 1884, the International Meridian Conference in Washington, DC set up a uniform time zone, it designated two time zones to India, Bombay time and Calcutta time. During the late 1880s, Madras time and Port Blair time also came into use.

In 1906, the meridian passing through Allahabad at 82.5 degrees East longitude was declared as the central meridian for India. In 1947, the Indian Government officially adopted the Indian Standard Time (IST) as the official time zone for India.

Who maintains Indian Standard Time?

Council of Scientific and Industrial Research- National Physical Laboratory (CSIR-NPL) currently maintains the Indian Standard Time.

Does India use Daylight Saving?

No, India does not use Daylight Saving.

It was only during the Sino-Indian War of 1962, and the Indo-Pakistani wars of 1965 and 1971, India briefly used Daylight Saving to reduce civilian energy consumption.

Which countries follow the Indian Standard Time?

Sri Lanka follows Indian Standard Time. It also does not observe Daylight Saving Time.

How many time zones are in India?

India follows only one time zone, Indian Standard Time (IST) which equals UTC+5.30.

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