- Category: Water Feature
- Type: Inland Water
- Latitude/Longitude: 51°49'34"N 3°16'7"W
- Eastings/Northings: 312655, 214948
- OS Grid: SO126149
- Mapcode Local: GBR YV.W1SV
- Mapcode Global: VH6CM.9C89
Location and coordinates are for the approximate centre of Llyn y Gran-fawr within this administrative area.
Geographic features and populated places may cross administrative borders.