Figure 5.

To calculate the cross-sectional area and the total length of a hexagonal planar coil, the spiral is approximated as a set of concentric hexagons. (a) The edge length, $l_n$, of the $n^{th}$ inner turn depends on the external edge, $l_{edge}$, and the trace width, w, and spacing, s. In the box (b), formulae for the equilateral hexagon perimeter $L_n$ and area $A_n$.