Which country uses Indian Standard Time nationwide?

India uses Indian Standard Time nationwide.

Indian Standard Time is fixed at UTC+05:30 and applies across the Republic of India, which uses one official time zone despite spanning more than 29 degrees of longitude. India does not currently observe daylight saving time.

The standard meridian is 82°30′ east longitude, near Mirzapur in Uttar Pradesh. Indian Standard Time came into force on 1 January 1906 during the British period, and the independent Indian government later established it as the official time for the whole country.

A common misconception is that India has separate official zones for its far eastern and western regions. Local sunrise varies substantially across the country, and proposals for additional zones have been discussed, but India’s official civil time remains unified. Assam tea gardens may informally use “Bagan Time,” one hour ahead, but that is not a national time zone.