Why there are only 5 Regular Solids

Are there any more Regular Solids to be made? Sadly no: and this becomes clear as you build them. Round any vertex the total sum of the angles can’t possibly sum to more than 360 degrees (a complete rotation round a single point); and the combinations we’ve seen here cover all the possible options. The table below shows the numbers and the possible outcomes as you try the many different combinations:

Flat shape Angle Number round each vertex Total degrees Shape
Triangle 60 3 180 Tetrahedron
Triangle 60 4 240 Octahedron
Triangle 60 5 300 Icosahedron
Triangle 60 6 360 no good: it just comes out flat
Square 90 3 270 Cube
Square 90 4 360 no good: it just comes out flat
Pentagon 108 3 324 Dodecahedron
Pentagon 108 4 432 no good: it doesn’t work at all
Hexagon 120 3 360 no good: it just comes out flat

And so it falls out – there are only 5 simple polyhedra. But there are lots more to come if we relax the rules a bit and move on to The 13 Semi-Regular (Archimedean) Solids.


The 5 Regular (Platonic) Solids
The 13 Semi-Regular (Archimedean) Solids