According to provisional results of 2011 census, Darjeeling Urban Agglomeration had a population of 132,016, out of which 65,839 were males and 66,177 were females. The sex ratio was 1005 females per 1,000 males. The 0–6 years population was 7,382. Effective literacy rate for the population older than 6 years was 93.17 per cent.
As per the 2001 census, the Darjeeling urban agglomeration (which includes Pattabong Tea Garden), with an area of 12.77 km², has a population of 109,163. Also, the town has an additional average diurnal floating population of 20,500-30,000, mainly consisting of tourists and visitors. The population density is 8548 per km². The sex ratio is 1017 females per 1000 males– which is higher than the national average. The town houses about 31% of its population in the slums. This is the result of the unprecedented urban growth due to the unsustainable migration in the area (mainly of daily wage earners) for better opportunity.
The town of Darjeeling has seen fluctuation in the growth of its population in the last century. However, growth in population has been more rapid from the 1970s onwards, exceeding the growth rates at the district level. The growth rate has touched the sky height of about 45% in the 1990s and thus is far above the national, state, and district average. The colonial town of Darjeeling was designed for a mere population of 10,000. So the population spurt has made the town more prone to the environmental problems in recent decades as the region is geologically relatively new with hosts of environmental problems and hence unstable in nature. Environmental degradation has adversely affected Darjeeling's appeal for tourists. The town as a district headquarters acts as the center of all types of economic activity, which attracts the rural folks of the district to migrate to the town for better opportunity. Besides, the pleasant climate of the town compels the people from the surrounding states to migrate and settle permanently in the region.
The major religion is Hinduism, followed by Buddhism. Christians and Muslims form the minority. The majority of the populace are ethnic Gorkhas. Indigenous ethnic groups include the Lepchas and Bhutias. The Indian Gorkha ethnic groups include Limbus, Rais, Yakkhas (Dewans), Sunuwars, Sherpas, Tamangs, Yolmos, Damais, Kamis, Newars (Pradhans), Magars, Bahuns and Chhetris. Other communities are the Bengalis, Marwaris, Anglo-Indians, Han Chinese, Biharis and Tibetans. Languages spoken in Darjeeling include (Nepali), which is the predominant language; others are Tibetan, Hindi, English and Bengali.