Lac-Duffy is a Unincorporated area located in Saint-Calixte; Montcalm, Quebec and has an elevation of 330 meters.

• Latitude: 46° 0' 36'' North   (decimal: 46.0100387)
• Longitude: 73° 55' 10'' West   (decimal: -73.9193194)
• Topography Feature Category: Unincorporated area
• Geographical Feature: Secteur résidentiel
• Canadian Province/Territory: Quebec
• Elevation: 330 meters
• Location: Saint-Calixte; Montcalm
• Atlas of Canada Locator Map: Lac-Duffy
• GPS Coordinate Locator Map: Lac-Duffy Lat/Long