One of the important indices of population concentration is the density of population. It is defined as the number of persons per sq km. The population density of India in 2011 was 382 per sq km.
The density of population was decreased in between 2001 and 2011. NCT of Delhi with population density 11, 297 is the most thickly populated UT. Among the states, Bihar is on the top of the list with a population density of 1,102 in 2011.
Source: India Book - A Reference Annual