List of states and union territories of India by population

India is a union of 29 states and 7 union territories. As of 2011, with an estimated population of 1.2 billion, India is the world's second most populous country after the People's Republic of China. India occupies 2.4 percent of the world's land surface area and is home to 17.5 percent of the world's population. After the Gangetic plains, the eastern and western coastal regions of the Deccan plateau are the most densely populated regions of India. The Thar desert in western Rajasthan is one of the most densely populated deserts in the world. The northern and north-eastern states along the Himalayas contain cold arid deserts with fertile valleys. These states have less population density due to indomitable physical barriers.

The first population census in British India was conducted in 1872. Since India's independence in 1947, a census has been conducted every 10 years, the first occurring in 1951. The census in India is conducted by the Office of the Registrar General and Census Commissioner under the Ministry of Home Affairs, and is one of the largest administrative tasks conducted by a federal government.