Kathmandu District (काठमाडौं जिल्ला; Nepal Bhasa: ये: जिल्ला) is a district located in Kathmandu Valley, Bagmati Province of Nepal. It is one of the 77 districts of Nepal, covers an area of , and is the most densely populated district of Nepal with 1,081,845 inhabitants in 2001, 1,744,240 in 2011 and 2,017,532 in 2021. The administrative headquarters of Kathmandu district is located in Kathmandu. The city has 21 post offices which handle mail from across the country and beyond, with Kathmandu DPO having 44,600 as its postal code for international mail delivery services like UPS or DHL Couriers etc.
Kathmandu district is one of the three districts located in Kathmandu Valley, which itself is located in the hills of Bagmati Province. The district is located from 27°27E to 27°49E longitude and 85°10N to 85°32N latitude.
The district is surrounded by:
East: Bhaktapur District and Kavrepalanchok District
West: Dhading District and Nuwakot District
North: Nuwakot District and Sindhupalchok District
South: Lalitpur District and Makwanpur District
The altitude of the district ranges from to above sea level.
In the urban center, the temperature fluctuates between 32 °C in summer (June–July) to -2 °C in winter (December–January). Except for the high hills including Chandragiri which has a temperate climate, Kathmandu district has a subtropical climate. The annual rainfall of the district is 176.4 ml.
Kathmandu district is a part of Kathmandu Valley, which is a melting pot of various cultural groups, ethnicities, races, languages and religions. This vibrant culture is illustrated in the culture of the natives of the district, known as Newars, who are a multiethnic, multiracial, multireligious people bound by a Sanskritized Sino-Tibetan language of Kirat origins known as Nepal Bhasa. All the ancient settlements of the district have specific street festivals (jatras) arranged according to specific dates of the Nepal Sambat calendar.