Forestdale is a village and census-designated place within the town of Sandwich in Barnstable County, Massachusetts, United States. The population of Forestdale was 4,099 at the 2010 census. It is the most populous of the three CDPs in Sandwich. The ZIP code of Forestdale is 02644.Forestdale is located in the southern part of Sandwich at 41°41′0″N 70°30′44″W / 41.68333°N 70.51222°W / 41.68333; -70.51222. It is bordered by the town of Mashpee to the south and by Otis Air National Guard Base to the west. Massachusetts Route 130 is the main route through the community, leading north to Sandwich village and south through Mashpee to Santuit in Barnstable.According to the United States Census Bureau, the Forestdale CDP has a total area of 4.2 square miles. 3.8 square miles of it is land, and 0.35 square miles of it is water.As of the census of 2000, there were 3,992 people, 1,307 households, and 1,049 families residing in the CDP. The population density was 415.5/km².