What is the difference between mean local time and Indian Standard Time (IST)?

The actual time (mean local time) at any place varies depending on its longitude. However, for convenience one time (Indian Standard Time) has been adopted for the whole of India. Mean local time can be converted to IST as follows:

(Typical variation of IST from mean local time is depicted in minutes)


Port Blair                           -41          

Guwahti                          -37

Patna                             -11

Lucknow                        +6

Delhi                             +21

Srinagar                       +31   

Panaji                           +35