This page explains how to convert a capacitor defined by its voltage and capacitance in to a capacity expressed in watt-hour. The aim is to compare capacitors to a batteries in term of stored energy. Fill the following fields, the value of the capacitance or capacitor will be updated automatically.

Farads [F]

Farads

Voltage [V]

Voltage [V]

Watt.hour [Wh]

Watt.hour [Wh]

Ampere.hour [Ah]

Ampere.hour [Ah]

To convert the capacitance expressed in Farads into a capacity expressed in Watts.hour, we will calculate the maximum energy the capacitor can store.

According to the Wikipedia capacitor page the energy \( W \) (expressed in joules) stored in a capacitor is given by the following formula:

$$ W_{(J)} = \dfrac{1}{2}CV^2 $$

One joule is equivalent to 1Ws in another words one joule is one Watt of energy spent during one second. We can deduce the energy stored in the capacitor expressed in Watts.second:

$$ W_{(Ws)} = \dfrac{1}{2}CV^2 $$

To get the energy in Watts.hour, divide \( W_{(Ws)} \) by 3600 (60 minutes x 60 secondes):

$$ W_{(Wh)} = \dfrac{1}{7200}CV^2 $$

To compare a capacitor with a battery capacity expressed in Ah, just divide by the voltage:

$$ C_{(Ah)} = \dfrac{1}{7200}CV $$

Last update : 02/09/2023