According to the United States Census Bureau, the town has a total area of 24.2 square miles (63 km²), of which 23.8 square miles (62 km²) is land and 0.4 square miles (1.0 km²) (1.53%) is water.

Ashby is bordered by New Ipswich, New Hampshire and Mason, New Hampshire to the north, Townsend to the east, Lunenburg to the southeast, Fitchburg to the south, and Ashburnham to the west.

Public transportation for Ashby is largely supplied by the Montachusett Regional Transit Authority (MART). MART operates fixed-route bus services, shuttle services, as well as paratransit services within the Montachusett Region.

At the 2010 census, there were 3,074 people, 1,105 households and 862 families residing in the town. The population density was 129.2 per square mile (49.9/km²). There were 1,191 housing units at an average density of 50.0 per square mile (19.3/km²). The racial makeup of the town was 97.1% White, 0.4% African American, 0.2% Native American, 0.3% Asian, 0.4% from other races, and 1.6% from two or more races. Hispanic or Latino of any race were 1.9% of the population.

...
Wikipedia