The Astor Bridge over the St. Johns River between Astor and Volusia. According to the United States Census Bureau, the CDP has a total area of 2.5 square miles (6.5 km sq), all of it land (this measurement seems to exclude Astor's network of canals, which extends over 4 miles (6.4 km) in length, providing river access for many of its residents.) Astor lies entirely within the boundaries of the Ocala National Forest.
Astor is primarily accessible by land via Florida State Road 40, which is the main highway through the community. State Road 40 bisects the Ocala National Forest, approaching Astor from the west and continuing east over the Astor Bridge across the St. Johns River to Volusia, in Volusia County.