Chwarel y Fan is a peak in the Black Mountains in south-eastern Wales. It is the highest rise on the long ridge which extends southeastwards from Rhos Dirion. The ridge continues southeastwards to the lesser summit of Bal-Mawr whose top is adorned by a trig point at 607 m above sea level. About 1 km southeast along the ridge is the lesser top of Bal-Bach at a height of just over 520 m. Chwarel y Fan is the county top of the historic county of Monmouthshire, and is also the highest point in the current local government area of Monmouthshire. The summit is on a thin ridge and is crowned by a cairn. On the other sides of the valleys: to the west is Pen Twyn Mawr and to the east is Black Mountain.