Coil Inductance Calculator


Use the Coil Inductance Calculator to calculate the inductance of air-cored single-layer solenoid, multi-layer solenoid and flat spiral coils

The formula for calculating the inductance of an air-core single-layer solenoid is:

L=\frac{r^2N^2}{9r+10l}\; \mu H

The formula for calculating the inductance of an air-core multi-layer solenoid is:

L=\frac{0.8(r^2N^2)}{6r+9l+10d}\; \mu H

The formula for calculating the inductance of an air-core flat spiral coil is:

L=\frac{r^2N^2}{8r+11d}\; \mu H

Where
N = Number of turns
r = Coil radius in inches
l = Coil length in inches
d = Winding depth in inches
L = Inductance in microhenrys (μH)

Coil Inductance Calculator Diagram
Coil dimensions for calculating inductance

Using the Coil Inductance Calculator

Coil Geometry: Select the geometry of your coil from the list. You can choose from single-layer solenoid, multi-layer solenoid and flat spiral coil forms

Length: Enter the coil length, measured as depicted in the diagram above

Diameter: Enter the coil diameter, measured as depicted in the diagram above

Depth: Enter the winding depth, as depicted in the diagram. This does not apply to a single-layer solenoid coil

Number Of Turns: Enter the total number of turns

Selecting units: You can choose your preferred units of measurement through selecting the units cells and clicking the downwards pointing arrow to display a list of available options

Learn As You Go: This feature displays a live example of how to calculate self-inductance using the figures that you enter

Select your coil geometry, enter the dimensions, and select the units
mm
mm

How To Calculate Coil Inductance

Enter some values to get started!

Reference: ARRL – The Radio Amateur’s Handbook