Capacitance Reactance Calculator

How Capacitive Reactance Works?

Capacitive reactance (symbol XC) is the resistance offered by a capacitor to an AC (alternating current) signal. It works like resistance but it changes which depends on the frequency of the signal and the value of the capacitor.

The formula to calculate capacitive reactance is:

XC = 1 / (2 × π × f × C)

Where:

• XC is the reactance in ohms (Ω)
• f is the frequency in hertz (Hz)
• C is the capacitance in farads (F)

Key Points:

• Reactance is high at low frequencies and low at high frequencies.
• For DC (0 Hz) reactance is infinite—capacitor blocks it.
• For high-frequency AC, the capacitor easily allows current to pass.

Example:

• A 1 µF capacitor at 50 Hz has a reactance of about 3.2 kΩ.
• The same capacitor at 10 kHz will have a reactance of just 16 Ω.

This is why, capacitors are commonly used to filter out DC and pass AC especially in power supplies and signal processing.

Calculating Capacitance Output Current Capacity

Now since we know how to calculate the reactance of the capacitor, we can now easily calculate the output current capacity of that capacitor using the following Ohm's law calculator tool.

Enter the reactance value inside the "Resistance" field.

Add the RMS voltage of the AC voltage or the DC voltage, in the "Voltage" field.

Press "Calculate" to get the final result, that is the maximum current delivering capacity of the capacitor.