Home to 203,413 people as of 2000 census, Fremont is the fourth most populous city in the Bay Area. At 92 square miles, it is California's fifth largest city.

Fremont has the largest Afghani population in the United States and hence became a center of media attention when the US attacked Afghanistan in 2001.

According to the United States Census Bureau, the city has a total area of 225.6 km² (87.1 mi²). 198.6 km² (76.7 mi²) of it is land and 27.0 km² (10.4 mi²) of it is water. The total area is 11.97% water.

There are 68,237 households out of which 40.2% have children under the age of 18 living with them, 62.7% are married couples living together, 9.2% have a female householder with no husband present, and 23.5% are non-families. 16.5% of all households are made up of individuals and 4.1% have someone living alone who is 65 years of age or older. The average household size is 2.96 and the average family size is 3.34.

In the city the population is spread out with 25.8% under the age of 18, 7.7% from 18 to 24, 36.8% from 25 to 44, 21.4% from 45 to 64, and 8.3% who are 65 years of age or older. The median age is 34 years. For every 100 females there are 101.1 males. For every 100 females age 18 and over, there are 99.2 males.

The median income for a household in the city is $76,579, and the median income for a family is $82,199. Males have a median income of $59,274 versus $40,625 for females. The per capita income for the city is $31,411. 5.4% of the population and 3.6% of families are below the poverty line. Out of the total people living in poverty, 5.9% are under the age of 18 and 6.2% are 65 or older.