According to the United States Census Bureau, the town has a total area of 20.7 square miles (53.6 km_), of which, 19.8 square miles (51.3 km_) of it is land and 0.9 square miles (2.4 km_) of it (4.39%) is water.
The Saugatuck River begins to the north in Redding. It flows through the town and ends in the Long Island Sound by neighboring Westport. Weston is bordered by Westport to the south, Wilton to the west, Redding to the north, Easton to the east, and Fairfield to the southeast.
As of the census of 2000, there were 10,037 people, 3,312 households, and 2,811 families residing in the town. The population density was 507.0 people per square mile (195.7/km.). There were 3,532 housing units at an average density of 178.4/sq mi (68.9/km.). The racial makeup of the town was 95.75% White, 0.88% African American, 0.11% Native American, 1.94% Asian, 0.10% Pacific Islander, 0.25% from other races, and 0.98% from two or more races. Hispanic or Latino of any race were 2.05% of the population.
There were 3,312 households out of which 49.8% had children under the age of 18 living with them, 78.4% were married couples living together, 5.0% had a female householder with no husband present, and 15.1% were non-families. 11.2% of all households were made up of individuals and 4.9% had someone living alone who was 65 years of age or older. The average household size was 3.03 and the average family size was 3.28.
In the town the population was spread out with 33.2% under the age of 18, 2.7% from 18 to 24, 25.5% from 25 to 44, 28.9% from 45 to 64, and 9.7% who were 65 years of age or older. The median age was 40 years. For every 100 females there were 96.5 males. For every 100 females age 18 and over, there were 92.9 males.
The 2007 CERC Town Profile reports the median income for a household in the town was $170,758, and the median income for a family was $162,032. Males had a medianincome of $100,000 versus $55,956 for females. The per capita income for the town was $74,817. About 1.3% of families and 1.9% of the population were below the poverty line, including 1.3% of those under age 18 and 1.5% of those age 65 or over.