〰️ Reactance Calculator (Xc & Xʟ)
Enter a frequency and a capacitance or inductance to get its reactance — the frequency-dependent AC opposition in ohms.
Capacitive reactance Xc
159.2 Ω
Capacitive reactance Xc = 1 ÷ (2πfC) falls as frequency rises — a capacitor passes high frequencies and blocks DC. Reactance is the frequency-dependent AC "resistance" of the component, in ohms. 🔒 In your browser.
How the reactance calculator (xc & xʟ) works
Reactance is the opposition a capacitor or inductor presents to alternating current, measured in ohms but varying with frequency. Capacitive reactance is Xc = 1 ÷ (2πfC): it falls as frequency rises, so a capacitor blocks DC and passes high frequencies. Inductive reactance is Xʟ = 2πfL: it rises with frequency, so an inductor passes DC and opposes high frequencies. Pick the component type, enter the frequency and the capacitance or inductance (with convenient units), and the tool returns the reactance.
Reactance is the imaginary part of impedance; in a circuit with resistance too, the total opposition is the impedance Z = √(R² + X²). At the resonant frequency of an LC pair the capacitive and inductive reactances are equal and cancel — see the LC resonant-frequency calculator.
Frequently asked questions
How do I calculate capacitive reactance?
Xc = 1 ÷ (2πfC), with f in hertz and C in farads. A 1 µF capacitor at 1 kHz has a reactance of about 159 Ω. Doubling the frequency halves the reactance.
How do I calculate inductive reactance?
Xʟ = 2πfL, with f in hertz and L in henries. A 10 mH inductor at 1 kHz has a reactance of about 63 Ω. Doubling the frequency doubles the reactance.
What is the difference between reactance and resistance?
Resistance opposes current the same at all frequencies and dissipates power as heat. Reactance opposes alternating current in a frequency-dependent way and stores energy (in a capacitor's field or an inductor's field) rather than dissipating it.
Why does capacitor reactance decrease with frequency?
A capacitor charges and discharges more times per second as frequency rises, so more current flows for the same voltage — which means lower reactance. At DC (0 Hz) its reactance is infinite, blocking current entirely.
What is impedance versus reactance?
Impedance Z combines resistance R and reactance X into the total opposition to AC: Z = √(R² + X²) in magnitude. Reactance is just the part contributed by capacitors and inductors; this tool gives that reactance.