Legglass is bounded on the north by Legnagrow townland, on the west by Mully Upper townland and on the east by Eshveagh, Killykeeghan and Tromogagh townlands. Its chief geographical features are Cuilcagh Mountain, on whose western slope it lies, mountain streams, forestry plantations, mountain pools and a spring well. The townland is traversed by minor public roads and rural lanes. The townland covers 215 statute acres.