Impedance Calculator

Calculate the impedance of an RLC circuit in series or parallel configuration. Enter your resistance (R), inductance (L), capacitance (C), and signal frequency (f) to get the total impedance (Z), inductive reactance (XL), capacitive reactance (XC), phase angle (φ), resonant frequency (f₀), and Q factor — all in one calculation. Also try the calculate Inductor Energy Stored Energy (E).

Circuit Configuration *

Ω

Resistance in ohms

mH

Inductance in millihenries

Capacitance value

Frequency of the AC signal

Results

Total Impedance (Z)

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Inductive Reactance (XL)

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Capacitive Reactance (XC)

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Phase Angle (φ)

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Resonant Frequency (f₀)

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Q Factor

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Frequently Asked Questions

What is an RLC circuit?

An RLC circuit is an electrical circuit containing a resistor (R), an inductor (L), and a capacitor (C) connected in series or parallel. These circuits are widely used in radio receivers, televisions, filters, and oscillators because of their frequency-selective behavior. See also our Watts to Amps Calculator.

How do you calculate the impedance of a series RLC circuit?

For a series RLC circuit, impedance is calculated as Z = √(R² + (XL − XC)²), where XL = 2πfL is the inductive reactance and XC = 1/(2πfC) is the capacitive reactance. The result is in ohms (Ω).

How do you calculate the impedance of a parallel RLC circuit?

For a parallel RLC circuit, the admittance Y = √((1/R)² + (1/XL − 1/XC)²), and impedance Z = 1/Y. At resonance, a parallel RLC circuit has maximum impedance, which is the opposite behavior of a series circuit.

What is the impedance of an RLC circuit?

Impedance (Z) is the total opposition that a circuit offers to alternating current, measured in ohms. It combines resistance (purely dissipative) with reactance (frequency-dependent, from inductors and capacitors) into a single complex quantity. You might also find our Capacitor Energy Calculator useful.

Does impedance of an RLC circuit depend on resistance?

Yes. Resistance (R) is a constant component of impedance and does not change with frequency. Reactances XL and XC are frequency-dependent. The total impedance Z = √(R² + (XL − XC)²) for a series circuit, so both resistance and reactance together determine Z.

What is the resonant frequency of an RLC circuit?

The resonant frequency is f₀ = 1 / (2π√(LC)), where L is inductance and C is capacitance. At resonance, XL equals XC, and the impedance of a series circuit is at its minimum (equal to R alone), while a parallel circuit reaches maximum impedance.

What is the phase angle in an RLC circuit?

The phase angle φ describes the phase difference between the voltage and current in the circuit. It is calculated as φ = arctan((XL − XC) / R) for a series circuit. A positive angle means the circuit is inductive; negative means capacitive; zero means resistive (at resonance).

What is the Q factor of an RLC circuit?

The Q factor (quality factor) measures how underdamped a resonator is, or how narrow its resonant bandwidth is. For a series RLC circuit, Q = (1/R)√(L/C). A higher Q factor means sharper resonance and lower energy loss relative to stored energy.