Amherst, NH has a population of 670 and is the 17,737th largest city in the United States. The population density is 922 per sq mi which is 553% higher than the New Hampshire average and 918% higher than the national average. The median age in Amherst is 45 which is approximately 7% higher than the New Hampshire average of 42. In Amherst, 70% of the population over 15 years of age are married, 99% speak English and 0% speak Spanish. 18% of Amherst residents were born in New Hampshire, 74% were born out of state, 3% were born outside of the United States and 5% were foreign born.