Though British India did not officially adopt the standard time zones until 1905, when the meridian passing east of Allahabad at 82.5° E longitude was picked as the central meridian for India, corresponding to a single time zone for the country ( UTC+05:30). Local time zones were also set up in the important cities of Bombay and Calcutta and as Madras time was intermediate to these, it was one of the early contenders for an Indian standard time zone. In 1802 Madras Time was set up by John Goldingham and this was later used widely by the railways in India.

For example, the Jantar Mantar observatory built by Maharaja Sawai Jai Singh in Jaipur in 1733 contains large sundials, up to 27 m (90 ft) high, which were used to accurately determine the local time. For most of India's history, ruling kingdoms kept their own local time, typically using the Hindu calendar in both lunar and solar units. Despite these early advances, standard time was not widely used outside astronomy.

The Surya Siddhanta also described a method of converting local time to the standard time of Ujjain. Taking a day to be 24 hours, the smallest time unit, prāṇa, or one respiratory cycle, equals 4 seconds, a value consistent with the normal breathing frequency of 15 breaths/min used in modern medical research. A nakṣatra māsa, or astronomical month, consists of 30 days. The ghalikā is 60 palas, and the nakṣatra ahórātra, or astronomical day, contains 60 ghalikās. Time that is measurable is that which is in common use, beginning with the prāṇa (or, the time span of one breath). The day used by ancient Indian astronomers began at sunrise at the prime meridian of Ujjain, and was divided into smaller time units in the following manner: The book described the thousands years old customs of the prime meridian, or zero longitude, as passing through Avanti, the ancient name for the historic city of Ujjain, and Rohitaka, the ancient name for Rohtak ( 28★4′N 76☃8′E / 28.900°N 76.633☎ / 28.900 76.633 ( Rohitaka (Rohtak))), a city near the Kurukshetra. The 4th century CE astronomical treatise Surya Siddhanta postulated a spherical earth. See also: Hindu units of time and History of measurement systems in India

India time zone gmt