Delhi has a population of more than 15 million people (Est. 2005) making it the 3rd largest metropolitan area in India after Mumbai and Kolkata. There are 827 women for every 1000 men and the metropolis has a literacy rate of 78.5%. The ratio of urban population stands at approximately 90%. Delhi has one of the highest per capita incomes in India and is one of the fastest growing metropolitan areas in Asia.

According to the census carried out by the Indian Government in 2001, 13.0 million people lived in the Delhi metropolitan area. However, it is now estimated that more than 15.0 million people live in Delhi and its surrounding suburbs with migrants accounting for 60% of the increase in population. If you include the surrounding satellite towns of NOIDA, Gurgaon, Faridabad and Ghaziabad, the population is estimated to be over 20 million.

Due to relatively high employment opportunities and better living conditions, Delhi has attracted millions of people from rural areas in neighbouring Haryana, Punjab, Uttar Pradesh and Bihar. Delhi's state Government has come under tremendous pressure as the city's infrastructure struggles to keep pace with the rising population. In 2001, the state Government of Delhi launched a 'master plan' to allocate more residential, commercial and industrial areas in the region and also decided to invest billions of dollars in city's infrastructure.

Hindus form the religious majority, but large, vibrant communities of Sikhs, Muslims, Jains and Christians bring diversity. Punjabis and Jats are large ethnic communities, but a collage of peoples from almost every Indian state inhabits the city. Large numbers of Kashmiris also inhabit the city and its outskirt areas. 83.67% of Delhi's population practices Hinduism, 9.2% Islam, 6.1% Sikhism and 0.9% Christianity. Other minorities include Jains, Buddhists and Jews.

The principal spoken language is Hindi-Urdu (sometimes called Hindustani). The principal written language is Hindi. Other common languages spoken are English and Punjabi. Since Delhi is the capital, linguistic groups from all over India are represented including: Tamil, Kannada, Telegu and many others.