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Capacitive Reactance Calculator

Use our Capacitive Reactance Calculator a free online tool to calculate the impedance of the capacitor in an electrical circuit. Enter the values of frequency and capacitance to calculate reactance.

Capacitive Reactance Formula

The formula is: XC = 1 / 2πfCC

Capacitive Reactnace Calculator

Capacitive Reactance

The capacitor as a device which passes ac and in which the only opposition to the alternating current has been the normal circuit resistance present in any conductor. However, capacitors themselves offer a very real opposition to current flow. This opposition arises from the fact that, at a given voltage and frequency, the number of electrons which go back and forth from plate to plate is limited by the storage ability-that is, the capacitance-of the capacitor. As the capacitance is increased, a greater number of electrons change plates every cycle, and (since current is a measure of the number of electrons passing a given point in a given time) the current is increased.

Increasing the frequency will also decrease the opposition offered by a capacitor. This occurs because the number of electrons which the capacitor is capable of handling at a given voltage will change plates more often. As a result, more electrons will pass a given point in a given time (greater current flow). The opposition which a capacitor offers to ac is therefore inversely proportional to frequency and to capacitance. This opposition is called Capacitive Reactance. You may say that capacitive reactance decreases with increasing frequency or, for a given frequency, the capacitive reactance decreases with increasing capacitance. The symbol for capacitive reactance is XC .

The XC varies inversely with the product of the frequency and capacitance. The formula is:

XC = 1 / 2πfcC
XC is capacitive reactance in Ω ohms
fc is frequency in Hertz
C is capacitance in Farads
π is 3.1416 constant


  • XC depends on the frequency of the applied voltage and the amount of capacitance.
  • XC is less for more capacitance.
  • XC is less for higher frequencies.