The average household size was 2.45 and the average family size was 2.97. For every 100 females age 18 and over, there were 88.8 males.
In the town, the population was spread out with 12.8% under the age of 18, 50.0% from 18 to 24, 17.2% from 25 to 44, 13.4% from 45 to 64, and 6.6% who were 65 years of age or older. The median income for a household in the town was ,017, and the median income for a family was ,237.
The racial makeup of the town was 76.7% White, 5.10% Black or African American, 0.21% Native American, 9.02% Asian, 0.09% Pacific Islander, 2.89% from other races, and 3.35% from two or more races.
There were 9,174 households out of which 27.0% had children under the age of 18 living with them, 36.4% were married couples living together, 10.8% had a female householder with no husband present, and 50.4% were non-families.
Of all households 28.6% were made up of individuals and 8.6% had someone living alone who was 65 years of age or older.
The earliest known document of the lands now comprising Amherst is the deed of purchase dated December 1658 between John Pynchon of Springfield and three native inhabitants, referred to as Umpanchla, Quonquont, and Chickwalopp.
According to the deed, "ye Indians of Nolwotogg (Norwottuck) upon ye River of Quinecticott (Connecticut)" sold the entire area in exchange for "two Hundred fatham of Wampam & Twenty fatham, and one large Coate at Eight fatham wch Chickwollop set of, of trusts, besides severall small giftes" [sic]. The Amherst 250th Anniversary Celebration Committee was established to oversee the creation and implementation of townwide activities throughout 2009.
The highest point in the town is on the northern shoulder of Mount Norwottuck; the peak is in Granby but the town's high point is a few yards away and is about 1100 feet.