Wolfram|Alpha has coils calculators. Solve problems related to maximal magnetic flux density in a circular coil; circular current loops; Helmholtz coils; the magnetic field in an infinitely long solenoid or ideal spherical solenoid; inductance factor; inductance of a coil; saturation current; self‐inductance of a single‐layer circular coil, circular coil of small radius or rectangular cross‐section coil; single- or multi-layer air core solenoid inductance; inductance for a multi-layer air core solenoid with a rectangular cross section; single-layer air core short helical coil inductance; spiral coil inductance; and conical coil inductance.
