Blanchester, OH has a population of 4,163 and is the 7,263rd largest city in the United States. The population density is 1,004 per sq mi which is 290% higher than the Ohio average and 1008% higher than the national average. The median age in Blanchester is 38 which is approximately 4% lower than the Ohio average of 39. In Blanchester, 57% of the population over 15 years of age are married, 99% speak English and 0% speak Spanish. 83% of Blanchester residents were born in Ohio, 17% were born out of state, 0% were born outside of the United States and 1% were foreign born.