Harmony, NJ has a population of 374 and is the 21,257th largest city in the United States. The population density is 302 per sq mi which is 30073% higher than the New Jersey average and 233% higher than the national average. The median age in Harmony is 46 which is approximately 15% higher than the New Jersey average of 40. In Harmony, 70% of the population over 15 years of age are married, 99% speak English and 0% speak Spanish. 60% of Harmony residents were born in New Jersey, 37% were born out of state, 1% were born outside of the United States and 2% were foreign born.