Bluffton, IN has a population of 9,702 and is the 4,024th largest city in the United States. The population density is 1,180 per sq mi which is 557% higher than the Indiana average and 1202% higher than the national average. The median age in Bluffton is 38 which is approximately 1% higher than the Indiana average of 37. In Bluffton, 57% of the population over 15 years of age are married, 97% speak English and 2% speak Spanish. 76% of Bluffton residents were born in Indiana, 21% were born out of state, 2% were born outside of the United States and 1% were foreign born.