Foster City is a planned city located in San Mateo County, California. As of the 2000 census, the city had a total population of 28,803.
According to the United States Census Bureau, the city has a total area of 51.6 km² (19.9 mi²). 9.7 km² (3.8 mi²) of it is land and 41.9 km² (16.2 mi²) of it is water. The total area is 81.13% water.
As of the census of 2000, there are 28,803 people, 11,613 households, and 7,931 families residing in the city. The population density is 2,957.7/km² (7,664.4/mi²). There are 12,009 housing units at an average density of 1,233.2/km² (3,195.6/mi²). The racial makeup of the city is 59.32% White, 2.09% African American, 0.12% Native American, 32.52% Asian, 0.58% Pacific Islander, 1.23% from other races, and 4.13% from two or more races. 5.32% of the population are Hispanic or Latino of any race.
There are 11,613 households out of which 30.5% have children under the age of 18 living with them, 57.7% are married couples living together, 7.7% have a female householder with no husband present, and 31.7% are non-families. 23.6% of all households are made up of individuals and 5.0% have someone living alone who is 65 years of age or older. The average household size is 2.47 and the average family size is 2.97.
In the city the population is spread out with 21.2% under the age of 18, 5.9% from 18 to 24, 35.3% from 25 to 44, 27.6% from 45 to 64, and 10.1% who are 65 years of age or older. The median age is 38 years. For every 100 females there are 96.8 males. For every 100 females age 18 and over, there are 93.9 males.
The median income for a household in the city is $95,279, and the median income for a family is $106,099. Males have a median income of $77,916 versus $51,157 for females. The per capita income for the city is $45,754. 2.9% of the population and 1.7% of families are below the poverty line. Out of the total people living in poverty, 1.6% are under the age of 18 and 5.6% are 65 or older.