The wire is then assumed to have the conductivity of copper. If the wire diameter or winding thickness is not explicitly requested, the coil is modeled as a zero thickness current sheet. Except for the circular solenoid of round wire, the formulas assume uniform current density throughout the winding, modified only when skin effect is included. In the cases that assume uniform current density, there is no correction for empty space in the winding. This correction, in microhenrys, is added to the inductance.
All calculations assume both the core material and the wire are non-magnetic.
The program may be configured to accept dimensions in either centimeters or inches. This is a compile-time option. Formulas for long coils. Butterworth's expansions for thick circular coils. Formulas for short, thin coils.