As of the census of 2010, there were 561 people, 230 households, and 156 families residing in the city. The population density was. There were 269 housing units at an average density of. The racial makeup of the city was 97.9% White, 0.2% Native American, 0.2% Asian, and 1.8% from two or more races. Hispanic or Latino of any race were 1.6% of the population. There were 230 households of which 33.0% had children under the age of 18 living with them, 53.5% were married couplesliving together, 10.9% had a female householder with no husband present, 3.5% had a male householder with no wife present, and 32.2% were non-families. 29.1% of all households were made up of individuals and 10.4% had someone living alone who was 65 years of age or older. The average household size was 2.44 and the average family size was 2.99. The median age in the city was 40.9 years. 26.2% of residents were under the age of 18; 6.1% were between the ages of 18 and 24; 22% were from 25 to 44; 29.8% were from 45 to 64; and 15.9% were 65 years of age or older. The gender makeup of the city was 50.4% male and 49.6% female.
2000 census
As of the census of 2000, there were 593 people, 239 households, and 162 families residing in the city. The population density was 704.6 people per square mile. There were 268 housing units at an average density of 318.4 per square mile. The racial makeup of the city was 97.13% White, 0.17% Native American, and 2.70% from two or more races. Hispanic or Latino of any race were 1.01% of the population. There were 239 households out of which 33.5% had children under the age of 18 living with them, 54.4% were married couples living together, 9.6% had a female householder with no husband present, and 32.2% were non-families. 29.3% of all households were made up of individuals and 14.2% had someone living alone who was 65 years of age or older. The average household size was 2.48 and the average family size was 3.06. In the city, the population was spread out with 28.3% under the age of 18, 7.3% from 18 to 24, 30.0% from 25 to 44, 20.7% from 45 to 64, and 13.7% who were 65 years of age or older. The median age was 36 years. For every 100 females, there were 96.4 males. For every 100 females age 18 and over, there were 90.6 males. The median income for a household in the city was $30,341, and the median income for a family was $39,375. Males had a median income of $25,469 versus $19,886 for females. The per capita income for the city was $15,034. About 6.6% of families and 10.3% of the population were below the poverty line, including 11.5% of those under age 18 and 15.8% of those age 65 or over.
Education
Gridley is served by USD 245 Southern Coffey County. School unification consolidated LeRoy and Gridley schools forming USD 245 in 2003. The Southern Coffey County High School mascot is Titans. LeRoy High School was closed through school unification. The LeRoy High School mascot was LeRoy Bluejays.
