Location of Calvin, Oklahoma
Calvin is located at (34.967315, -96.249811).
According to the United States Census Bureau, the town has a total area of 0.5 square miles (1.3 km2), all of it land.
As of the census of 2000, there were 279 people, 120 households, and 75 families residing in the town. The population density was 578.6 people per square mile (224.4/km²). There were 144 housing units at an average density of 298.6 per square mile (115.8/km²). The racial makeup of the town was 82.44% White, 10.75% Native American, and 6.81% of the population.
There were 120 households out of which 32.5% had children under the age of 18 living with them, 50.0% were married couples living together, 11.7% had a female householder with no husband present, and 36.7% were non-families. 33.3% of all households were made up of individuals and 15.8% had someone living alone who was 65 years of age or older. The average household size was 2.33 and the average family size was 2.96.
In the town the population was spread out with 25.1% under the age of 18, 9.7% from 18 to 24, 29.0% from 25 to 44, 21.1% from 45 to 64, and 15.1% who were 65 years of age or older. The median age was 32 years. For every 100 females there were 102.2 males. For every 100 females age 18 and over, there were 88.3 males.
The median income for a household in the town was $20,357, and the median income for a family was $23,409. Males had a median income of $17,083 versus $16,500 for females. The per capita income for the town was $10,651. About 21.6% of families and 27.0% of the population were below the poverty line, including 42.4% of those under the age of eighteen and 18.0% of those sixty five or over.