Lopérec (French pronunciation: [lɔpeʁɛk]; Breton: Lopereg) is a commune in the Finistère department of Brittany, in north-western France.

[4] Lopérec borders the Monts d'Arrée to the north and east, and the Châteaulin basin to the south.

The municipal boundary, stretching north-south and sloping toward the west, covers an area of 3,959 hectares (39.5 km2).

Numerous rivers are found in the area, including the Douffine which originates from the south-western slopes of Roc'h Cléguer en Brasparts and forms the municipal boundary to Pleyben.

Downstream, another small right-bank tributary of the Douffine forms the edge of Pont-de-Buis-lès-Quimerc'h municipality.