A cuboid has 12 edges. A cuboid is a box-like shaped polyhedron that has six rectangular plane faces. A cuboid also has six faces and eight vertices.
Knowing these latter two facts about a cuboid, the number of edges can be calculated with Euler’s polyhedral formula. This formula states that the number of faces (F) plus the number of vertices (V) minus the number of edges (E) equals 2, or F + V - E = 2.
By substituting 6 for V and 8 for V in this equation, it becomes 6 + 8 - E = 2, or 14 - E = 2. From this equation, it is simple to see that E equals 12.