Historical Indian Time Zones
They were named after Bombay and Calcutta
India currently has just one time zone, Indian Standard Time.
Indian Standard Time (IST) is 5 hours and 30 minutes ahead of GMT . It has not always been the same.
Railway Time or Madras Time
India's Time Zones were first established in 1884. Originally there were two time zones, Bombay Time and Calcutta Time.In the very early days of railways in India, local time was observed at each large city, in common with practice in most other countries at the time. Because of their importance as commercial and economic centres, Bombay Time and Calcutta Time assumed special importance.
Theiy and were followed for many official purposes in the late 19th century (Bombay Time from 1884), effectively forming two time zones for British India.
Calcutta time was 5 hours, 30 minutes, and 21 seconds in advance of GMT, while Bombay Time was 4 hours and 51 minutes ahead of GMT.
Many railway companies, however, standardized on using Madras time as being in between Bombay and Calcutta times, and often this, rather than Bombay time, was used in Indian timetables from the late 1880s onward.
Bombay continued to have a different time (39 minutes behind IST) until 1955. IST, which is GMT plus 5.30 hrs, came into existence in 1905.
In certain time-zone maps, IST is also designated E*. With India's western and eastern borders some 2,000 km (1,250 miles) apart, India could well have three time zones! Like China, another huge country, India has chosen however to have a single time zone across the whole country. No Daylight Saving Time rules are applied either.