An Ruadh-stac has the classic triangular mountain shape formed by three steep ridges; the NE ridge is the least steep and the one usually used for ascent and descent by walkers. This ridge drops to the Bealach a' Choire Ghairbh, which links the mountain to Maol Cheann-dearg, which stands 2 km to the north across Coire an Ruidh Staic. The south ridge leads over the subsidiary top of Ruadh Stac Beag (758 metres) before descending towards Glen Carron over rough, boggy ground. The north and west side of the mountain are ringed by steep crags, making the NW ridge out of bounds for walkers.