Cwmfelinfach is a small village located in the Sirhowy valley of south-east Wales. It is part of the district of Caerphilly within the historic boundaries of Monmouthshire. It is located north of Wattsville, about 5 miles north of the nearest town Risca, and south of Blackwood. To the east the valley is bordered by the hills of Pen-y-Trwyn (1,028 ft / 313 m). To the west is Mynydd y Grug (1,132 ft / 345 m).