Westfield, MA has a population of 41,486 and is the 988th largest city in the United States. The population density is 897 per sq mi which is 42% higher than the Massachusetts average and 890% higher than the national average. The median age in Westfield is 38 which is approximately 4% lower than the Massachusetts average of 39. In Westfield, 52% of the population over 15 years of age are married, 86% speak English and 3% speak Spanish. 71% of Westfield residents were born in Massachusetts, 17% were born out of state, 2% were born outside of the United States and 9% were foreign born.