Work out diagonal of a cube instantly with clear inputs, formula shown and shareable results.
A cube has two kinds of diagonal: the face diagonal a√2 across a single square face, and the space diagonal a√3 from one corner to the opposite corner through the interior.
Space diagonal
d = a√3
Face diagonal
f = a√2
5√3 ≈ 8.660254 units.
The face diagonal is a√2; combining it with the perpendicular edge a gives √(2a² + a²) = a√3.