Johnstown, OH has a population of 4,999 and is the 6,477th largest city in the United States. The population density is 1,675 per sq mi which is 550% higher than the Ohio average and 1749% higher than the national average. The median age in Johnstown is 33 which is approximately 17% lower than the Ohio average of 39. In Johnstown, 57% of the population over 15 years of age are married, 97% speak English and 2% speak Spanish. 83% of Johnstown residents were born in Ohio, 15% were born out of state, 0% were born outside of the United States and 2% were foreign born.