This is a very simple web page that is intended to help you estimate the inductance of a coil. The limitation is that it be a Single-Layer Air-Core coil. The program uses formula published in the ARRL Handbook For Radio Amateurs.

If you need a more accurate reading, or the coil does not meet the Single-Layer Air-Core coil criteria, use an Inductance Bridge or Grid-Dip Meter to determine the inductance.

In the text areas on the right, enter the Coil Diameter, Coil Length, and Number Of Turns. You can use either inches or millimeters and you can mix and match. The estimated Inductance, in uh, and Coil Turns Spacing will be calculated. Recalculation is automatic. Just click outside the entry area after changing any input data.