Caldwell County is located in south central Texas, just below the Balcones escarpment, with Lockhart, population 12,500, situated only 30 miles south of the state capitol. The city of Luling, population 4,800, sits at the southern tip of the county, fourteen miles to the south. The county covers 544 square miles or 348,160 acres. The San Marcos River and the Plum Creek are the major water drainage courses. Roughly, the shape of Caldwell County might be compared to a square which is balanced on one corner. In general, the topography of the county varies from broad flat prairies and gently undulating surfaces in the north and northwest to sand hill regions on the south and east. Two marked differences are found in the topography of Caldwell County. The first is the fact that in the northern part of the county lies Kaegler Hills, part of the Cunejeda Mountains, which parallel and are a part of the Balcones escarpment from southwest to northwest Texas. The second peculiarity is the presence of Iron Mountains, known locally as the Sand Hills, which lie in the southern part of the county and which do not seem to belong to any particular formation.

Statistics from 1996 attributed the following to Caldwell County: