2020 census As of the
2020 census, Armonk had a population of 4,495. The median age was 44.1 years. 25.6% of residents were under the age of 18 and 19.4% of residents were 65 years of age or older. For every 100 females there were 90.9 males, and for every 100 females age 18 and over there were 87.3 males age 18 and over. 96.8% of residents lived in urban areas, while 3.2% lived in rural areas. There were 1,537 households in Armonk, of which 39.6% had children under the age of 18 living in them. Of all households, 66.9% were married-couple households, 10.9% were households with a male householder and no spouse or partner present, and 19.8% were households with a female householder and no spouse or partner present. About 19.2% of all households were made up of individuals and 13.5% had someone living alone who was 65 years of age or older. There were 1,172 households, out of which 44.5 percent had children under the age of 18 living with them, 74.7 percent were married couples living together, 7.7 percent had a female householder with no husband present, and 15.1 percent were non-families. 13.1 percent of all households were made up of individuals, and 6.0 percent had someone living alone who was 65 years of age or older. The average household size was 2.95 and the average family size was 3.23. In the CDP, the population was spread out, with 29.8 percent under the age of 18, 4.4 percent from 18 to 24, 27.2 percent from 25 to 44, 26.7 percent from 45 to 64, and 11.8 percent who were 65 years of age or older. The median age was 39 years. For every 100 females, there were 90.6 males. For every 100 females age 18 and over, there were 90.2 males.
Income and poverty As of the census of 2013, the median income for a household in the CDP was $159,530, and the median income for a family was $189,163. The per capita income for the CDP was $92,750. 1.3 percent of the population and 0.0 percent of families were below the poverty line. Out of the total population, 0.0 percent of those under the age of 18 and 3.9 percent of those 65 and older were living below the poverty line. ==Education==