According to the U.S. Census Bureau, the county has a total area of, of which is land and is water. It is the fifth-smallest county in Georgia by area. The majority of Peach County is located in the Lower Ocmulgee River sub-basin of the Altamaha River basin. A small portion of the northern edge of the county, north of Byron, is located in the Upper Ocmulgee River sub-basin of the Altamaha River basin. The very western tip of Peach County is located in the Upper Flint River sub-basin of the ACF River Basin.
At the 2000 census there were 23,668 people, 8,436 households, and 5,997 families living in the county. The population density was 60/km². There were 9,093 housing units at an average density of 23/km². The racial makeup of the county was 51.27% White, 45.37% Black or African American, 0.33% Native American, 0.33% Asian, 0.03% Pacific Islander, 1.83% from other races, and 0.84% from two or more races. 4.22% of the population were Hispanic or Latino of any race. Of the 8,436 households 33.60% had children under the age of 18 living with them, 47.00% were married couplesliving together, 19.60% had a female householder with no husband present, and 28.90% were non-families. 22.60% of households were one person and 7.80% were one person aged 65 or older. The average household size was 2.68 and the average family size was 3.14. The age distribution was 26.00% under the age of 18, 14.90% from 18 to 24, 27.50% from 25 to 44, 21.70% from 45 to 64, and 9.80% 65 or older. The median age was 32 years. For every 100 females, there were 93.60 males. For every 100 females age 18 and over, there were 89.80 males. The median household income was $34,453 and the median family income was $41,570. Males had a median income of $33,357 versus $24,440 for females. The per capita income for the county was $16,031. About 15.20% of families and 20.20% of the population were below the poverty line, including 24.50% of those under age 18 and 13.50% of those age 65 or over.
2010 census
At the 2010 census, there were 27,695 people, 9,958 households, and 6,934 families living in the county. The population density was. There were 11,050 housing units at an average density of. The racial makeup of the county was 48.3% white, 45.9% black or African American, 0.8% Asian, 0.2% American Indian, 3.2% from other races, and 1.5% from two or more races. Those of Hispanic or Latino origin made up 6.8% of the population. In terms of ancestry, 11.0% were American, 7.1% were English, and 5.8% were Irish. Of the 9,958 households, 34.6% had children under the age of 18 living with them, 45.1% were married couples living together, 19.2% had a female householder with no husband present, 30.4% were non-families, and 24.8% of households were made up of individuals. The average household size was 2.58 and the average family size was 3.07. The median age was 33.3 years. The median household income was $41,014 and the median family income was $53,708. Males had a median income of $40,919 versus $29,328 for females. The per capita income for the county was $18,681. About 19.1% of families and 25.4% of the population were below the poverty line, including 44.6% of those under age 18 and 14.0% of those age 65 or over.
