Coil Capacitance Calculator

Use the Coil Capacitance Calculator to calculate the self-capacitance of air-cored single-layer solenoid coils, and learn how with the integrated live example

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

$C= HD\; pF$

Where
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

$\frac{Length}{Diameter}=\frac{15}{5}=3$

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

$H=0.61$

Substituting it into the equation:

$C= 0.61\times 5=3.05\; pF$

Coil Capacitance Calculator Diagram — *Coil dimensions for calculating capacitance*

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

How To Calculate Coil Capacitance: 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)

The result is calculated and updated automatically as you enter different numbers or change between the input fields. If the calculated result hasn’t updated after you’ve finished entering your values, click or tap on the result.

Reference: Radiotron Designer’s Handbook