county has a total area of 1256 sqmi, of which 16 sqmi (1.3%) are covered by water. Bexar County is in south-central Texas, about 190 mi west of Houston and 140 miles from both the US-Mexican border to the southwest and the Gulf of Mexico to the southeast.

The Balcones Escarpment bisects the county from west to northeast; to the north of the escarpment are the rocky hills, springs