Coil Capacitance Calculator

Use the Coil Capacitance Calculator to calculate the self-capacitance of air-cored single-layer solenoid coils. With automated referencing and data interpolation for higher accuracy results

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

C= HD\; pF

D = Coil diameter in centimetres
H = Factor corresponding to coil length/diameter ratio in Table 1
C = Capacitance in picofarads

Example: Calculate the self-capacitance of a coil that has a length of 15cm and diameter of 5cm


Look up the number corresponding to a length to diameter ratio of 3 in Table 1:


Substituting it into the equation:

C= 0.61\times 5=3.05\; pF

Coil Capacitance Calculator Diagram
Coil dimensions for calculating capacitance
Coil Capacitance Table
Table 1

Using the Coil Capacitance Calculator

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

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

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-capacitance using the figures that you enter (Note: The coil capacitance calculator uses value averaging and data interpolation for higher accuracy so may display values for H that are not shown in Table 1)

Enter the dimensions of your coil and select the units

How To Calculate Coil Capacitance

Enter some values to get started!

Reference: Radiotron Designer’s Handbook