It is 716.6 m (2,351 ft) high and is often hiked as part of the Horseshoe Walk, a traverse of the four main peaks in the Brecon Beacons.

At 716.7 m (2,351 ft),[1] Fan y Big lies at the western tip of the Gwaun Cerrig Llwydion plateau.

The summit is smooth and grassy, but marked by a cairn, which stands on the edge of its precipitous western face.

[3] The peak is prominent on the north facing escarpment of the central part of the Brecon Beacons and three footpaths meet at the summit.

The lower slopes of the hill are formed from sandstones and mudstones of the underlying Senni Formation.