Capacitive Reactance Calculator
Calculate capacitive reactance from frequency and capacitance.
Formula
XC = 1/(2πfC).
What Is Capacitive Reactance?
Capacitive reactance is the opposition a capacitor presents to alternating current. Unlike resistance, it changes with frequency: higher frequency or greater capacitance produces lower capacitive reactance.
Example Calculation
For C = 100 μF (0.0001 F) at 50 Hz, XC = 1/(2π × 50 × 0.0001) ≈ 31.83 Ω.
Factors That Affect the Result
Frequency must be in hertz and capacitance in farads. Doubling frequency halves XC, and doubling capacitance also halves XC. Real capacitors also have equivalent series resistance and parasitic effects not represented by the ideal formula.
Interpreting the Result
A low XC means the capacitor allows AC current to pass more readily at that frequency. At DC, frequency approaches zero and the ideal capacitor’s steady-state reactance tends toward infinity.
Frequently Asked Questions
Why does reactance fall as frequency rises?
A capacitor charges and discharges more frequently, so it opposes higher-frequency AC less strongly.
Is XC measured in ohms?
Yes, capacitive reactance has units of ohms.
Can I enter microfarads directly?
No. Convert μF to F by multiplying by 10⁻⁶.
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Formula and Practical Limits
Capacitive reactance is XC = 1/(2πfC). It decreases as frequency or capacitance increases. Real capacitors also have equivalent series resistance, leakage and frequency-dependent behavior.