HecaWorld Online Inductance calculator.

The formula for the inductance is given as L = (d^2*n^2)/(18*d + 40*l); where L is in microHenry, d and l are in inches (convert your unit to inches if not originally measured in inches, and n is a simple integer number representing the number of coil windings.

Find an appropriate material to use as a ‘former’ on which to wind the coil. We usually use a 5mm drill bit, but as we showed in this video, you don’t have to use 5mm drill bit if you don’t have one. You can use anyone and still achieve similar result.

Measure the diameter and length with a digital caliper for more accurate value. You don’t have to be too precise to the decimal digits as you can easily adjust the final product to reflect your intended inductance.