Grindstone, PA has a population of 385 and is the 21,082nd largest city in the United States. The population density is 302 per sq mi which is 9% higher than the Pennsylvania average and 233% higher than the national average. The median age in Grindstone is 36 which is approximately 11% lower than the Pennsylvania average of 41. In Grindstone, 68% of the population over 15 years of age are married, 96% speak English and 0% speak Spanish. 89% of Grindstone residents were born in Pennsylvania, 8% were born out of state, 0% were born outside of the United States and 3% were foreign born.