In geometry, a cuboid is a hexahedron, a six-faced solid. Its faces are quadrilaterals. Cuboid means "like a cube", in the sense that by adjusting the lengths of the edges or the angles between faces, a cuboid can be transformed into a cube. In mathematical language a cuboid is a convex polyhedron whose polyhedral graph is the same as that of a cube.^[1][2]

A special case of a cuboid is a rectangular cuboid, with six rectangles as faces and adjacent faces meeting at right angles. A cube is a special case of a rectangular cuboid, with six square faces meeting at right angles.^[1][3]

In attempting to classify cuboids by their symmetries, S. A. Robinson found that there were at least 22 different cases, "of which only about half are familiar in the shapes of everyday objects".^[4]

By Euler's formula the numbers of faces F, of vertices V, and of edges E of any convex polyhedron are related by the formula

$${\displaystyle F+V-E=2.}$$

In the case of a cuboid this gives 6 + 8 – 12 = 2; that is, like a cube, a cuboid has six faces, eight vertices, and twelve edges. Along with the rectangular cuboids, any parallelepiped is a cuboid of this type, as is a square frustum (the shape formed by truncation of the apex of a square pyramid).

• Cube
  (square faces)
• Rectangular cuboid
  (three pairs of
  rectangles)
• Trigonal trapezohedron
  (congruent rhombi)
• (congruent quadrilaterals)
• Quadrilateral frustum
  (apex-truncated
  square pyramid)
• Parallelepiped
  (three pairs of
  parallelograms)
• Rhombohedron
  (three pairs of
  rhombi)
• Trapezoidal prism
• Non-convex cuboid

• Lists of shapes