Single-Layer Air-Core Coil Calculator

Approximate inductance (L) of a single-layer coil. Approximation is close for coils
whose length is equal to or greater than 0.4 times diameter at frequencies
below about 30 MHz. Note also that coils with length greater than about 5 times
diameter are often physically impractical (and a waste of wire). Turns must be
evenly spaced.

Enter Coil Diameter:            
Enter Coil Length:                
Enter Number of Turns (N): 

L(µH) = (d2n2)/(18d + 40λ)

Where n is number of turns,
d is the diameter of the coil in inches and
λ is the length of the coil in inches
(inches = cm x .3937).



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