Brot-Dessous had an area, as of 2009, of 5 square kilometers (1.9 sq mi).
 Of this area, 0.62 km² (0.24 sq mi) or 12.5% is used for agricultural purposes, while 3.92 km² (1.51 sq mi) or 79.2% is forested.
  Of the rest of the land, 0.35 km² (0.14 sq mi) or 7.1% is settled (buildings or roads), 0.01 km² (2.5 acres) or 0.2% is either rivers or lakes and 0.06 km² (15 acres) or 1.2% is unproductive land.

Of the built up area, housing and buildings made up 1.8% and transportation infrastructure made up 5.3%.
 Out of the forested land, all of the forested land area is covered with heavy forests.
 Of the agricultural land, 0.6% is used for growing crops and 9.9% is pastures and 2.0% is used for alpine pastures.
 All the water in the municipality is flowing water.

The former municipality is located in the Boudry district.
 The municipal borders are the Areuse river and the crest of the Solmont mountain.
Brot-Dessous had an area, as of 2009, of 5 square kilometers (1.9 sq mi).  Of this area, 0.62 km² (0.24 sq mi) or 12.5% is used for agricultural purposes, while 3.92 km² (1.51 sq mi) or 79.2% is forested.   Of the rest of the land, 0.35 km² (0.14 sq mi) or 7.1% is settled (buildings or roads), 0.01 km² (2.5 acres) or 0.2% is either rivers or lakes and 0.06 km² (15 acres) or 1.2% is unproductive land.
Of the built up area, housing and buildings made up 1.8% and transportation infrastructure made up 5.3%.  Out of the forested land, all of the forested land area is covered with heavy forests.  Of the agricultural land, 0.6% is used for growing crops and 9.9% is pastures and 2.0% is used for alpine pastures.  All the water in the municipality is flowing water.
The former municipality is located in the Boudry district.  The municipal borders are the Areuse river and the crest of the Solmont mountain.
Brot-Dessous