Berneck has an area, as of 2006, of 5.6 km² (2.2 sq mi).
 Of this area, 49.6% is used for agricultural purposes, while 29.6% is forested.
 Of the rest of the land, 20.3% is settled (buildings or roads) and the remainder (0.5%) is non-productive (rivers or lakes).

The municipality is located in the former Unterrheintal district of the Rheintal Wahlkreis.
 It is between a line of hills and a side channel of the Rhine valley.
 It consists of the village of Berneck and the hamlets of Kobel, Rüden, Taa, Husen, Hinterburg and Buechholz.
Berneck has an area, as of 2006, of 5.6 km² (2.2 sq mi).  Of this area, 49.6% is used for agricultural purposes, while 29.6% is forested.  Of the rest of the land, 20.3% is settled (buildings or roads) and the remainder (0.5%) is non-productive (rivers or lakes).
The municipality is located in the former Unterrheintal district of the Rheintal Wahlkreis.  It is between a line of hills and a side channel of the Rhine valley.  It consists of the village of Berneck and the hamlets of Kobel, Rüden, Taa, Husen, Hinterburg and Buechholz.
Berneck, St. Gallen