Capacitance Calculator

Created by Bogna Szyk
Reviewed by Steven Wooding
Last updated: Dec 25, 2022


This capacitance calculator is a handy tool when designing a parallel plate capacitor. Such a capacitor consists of two parallel conductive plates separated by a dielectric (electric insulator that can be polarized). Read on if you want to find out what capacitance is, and how to calculate it using the capacitance equation.

💡 Are you working with a spherical capacitor instead? Check out the spherical capacitor calculator!

What is capacitance?

It is the ability of an object to store an electric charge. It only depends on the geometry of the capacitor and the choice of the dielectric material between the plates. In most cases, it does not depend on the potential difference or the charge stored on the plates.

Demonstration capacitor consisting of two parallel metal plates and air as the dielectric
Demonstration capacitor consisting of two parallel metal plates and air as the dielectric. Hannes Grobe / CC BY

Capacitance equation

How to calculate the capacitance, then? You need to use the following formula:

C=εAsC = \frac{\varepsilon A}{s}

where:

  • CC is the capacitance. It is measured in farads (symbol: F);
  • ε\varepsilon is the dielectric permittivity (a measure of resistance) in farads per meter;
  • AA is the area where the plates overlap; and
  • ss is the separation distance between the plates.

The permittivity depends on the dielectric material used. By default, this capacitance calculator uses the value of 8.854 pFm\mathrm{8.854 \ \frac{pF}{m}}, which is the permittivity of the vacuum. If you wish to change this value, click on the advanced mode button.

💡 One picofarad (pF) is equal to 10⁻¹² farads.

How to use the parallel plate capacitor calculator

  1. Determine what material will be used as the dielectric between two plates. In this example, we will use a vacuum.
  2. Once you decide on the material, find out its permittivity - for a vacuum, the value is 8.854 pFm\mathrm{8.854 \ \frac{pF}{m}}.
  3. Choose the area of plates. Let's say it's 120 mm2\mathrm{120 \ mm^2}.
  4. Measure the distance between the plates - we will assume 5 mm\mathrm{5 \ mm}.
  5. Insert all values into the capacitance calculator. It will find the value of capacitance for you! In our example, it is equal to 0.212 pF\mathrm{0.212 \ pF}. To learn about other units of capacitance check out our capacitance conversion tool.
  6. You can check the correctness of calculations with the capacitance equation.

What next?

Once you've calculated the capacitance of a single parallel plate capacitor, you can join it with other capacitors in series or parallel. It is fairly easy to calculate the total capacitance of such a system:

  • Capacitors in series follow the same rules as parallel resistors; and
  • Capacitors in parallel follow the same rules as resistors in series.

And, of course, we've got tools that can do this for you: the capacitors in series calculator and the parallel capacitor calculator.

Bogna Szyk
C = εA/s
Area (A)
in²
Separation distance (s)
in
Capacitance (C)
pF
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