Regular hexagon: side 6, area 93.5307, perimeter 36.
Solved from the side. A regular hexagon is six equilateral triangles sharing a centre, so area = 6 × (√3/4)a² = (3√3/2)a².
The circumradius equals the side (6), which is why a compass set to the side length draws a perfect hexagon on a circle.
The across-flats width (short diagonal = a√3 ≈ 10.3923) is the measurement stamped on hex nuts and bolt heads.
A regular hexagon tiles a plane with no gaps and wastes less perimeter per unit of area than any other regular polygon, which is why bees build honeycombs this way.
Next stepIf you measured across the flats instead, switch "Solve from" to Short diagonal to get the exact side.