As of the 2011 census, Gangtok's municipal population was roughly 100,286, though estimates suggest the wider metropolitan area has grown significantly since then. The city is a vibrant mosaic of ethnicities. The majority of the population comprises Indian Nepalis, alongside significant indigenous populations of Bhutias and Lepchas. There is also a notable presence of Marwaris, Biharis, and Bengalis who have settled here for business and government work.
Hinduism and Vajrayana Buddhism are the two dominant religions, followed seamlessly and often syncretically by the local population. Christianity and Islam represent smaller, yet active, minority faiths. The primary language of daily life is Nepali, though English is widely spoken and serves as the language of official government business and education. Gangtok boasts a high literacy rate of over 82%, and its residents enjoy a relatively high standard of living compared to national averages.