LC Parallel Impedance Calculator

Compute the AC impedance of a parallel LC circuit from inductance, capacitance, and frequency. The tool also returns the inductive reactance XL, capacitive reactance XC, and the resonant frequency.

Input

Calculate the combined impedance of a circuit with an inductor (L) and a capacitor (C) connected in parallel at a given frequency.

Inductance L

Enter the inductance of the coil in henries.

Capacitance C

Enter the capacitance of the capacitor in farads.

Frequency f

Enter the signal frequency in hertz.

Result

Combined impedance |Z|

103.817267Ω

The circuit behaves as inductive, below the resonant frequency.

Inductive reactance XL

62.831853 Ω

Capacitive reactance XC

159.154943 Ω

Resonant frequency f0

15,915.494309 Hz

Reference value assuming ideal components. |Z| = XL × XC / |XL − XC|, XL = 2πfL, XC = 1 / (2πfC).

How it works

For an ideal parallel LC circuit, the impedance magnitude is given by |Z| = XL × XC / |XL − XC|, where the inductive reactance is XL = 2πfL and the capacitive reactance is XC = 1 / (2πfC).
The frequency at which XL equals XC is the resonant frequency, calculated as f0 = 1 / (2π√(LC)). At this frequency the denominator |XL − XC| becomes zero, so the impedance theoretically diverges toward infinity.
Resonance in a parallel LC circuit is also called anti-resonance. Unlike series resonance, the impedance reaches its maximum (infinite in the ideal case) rather than its minimum. In real circuits the resistance of the inductor keeps the value finite.
Below the resonant frequency the circuit behaves as inductive, and above it as capacitive. This tool assumes lossless ideal components and gives a reference value that may differ from real hardware.

Reviews

Tell us what you think of this calculator.