Piqua, OH has a population of 20,743 and is the 2,089th largest city in the United States. The population density is 1,771 per sq mi which is 588% higher than the Ohio average and 1855% higher than the national average. The median age in Piqua is 38 which is approximately 4% lower than the Ohio average of 39. In Piqua, 51% of the population over 15 years of age are married, 98% speak English and 1% speak Spanish. 85% of Piqua residents were born in Ohio, 13% were born out of state, 1% were born outside of the United States and 1% were foreign born.