http://HAMwaves.com/antennas/inductance.html

The inductor calculator presented on this page is unique in that it employs the the n=0 sheath helix waveguide mode to determine the inductance of a coil, irrespective of its electrical length. This allows for more accurate inductance predictions at high frequencies.

Furthermore, the calculator closely follows the National Institute of Standards and Technology (NIST) methodology for applying round wire and non-uniformity correction factors and takes into account both the proximity effect and the skin effect.

All constructive comments are more than welcome.