RLC Impedance Calculator — Z, Phase Angle & Reactance
Enter R (resistance), L (inductance), C (capacitance) and the AC frequency to calculate inductive and capacitive reactance, total impedance Z and the phase angle between voltage and current.
Ω
mH
µF
Hz
Total opposition to AC current at the given frequency
- 1
Angular frequency ω = 2πf
2π × 1,000 = 6,283.19Converts frequency to radians per second. - 2
Inductive reactance XL = ωL
6,283.19 × 0.01 = 62.8319 - 3
Capacitive reactance XC = 1 ÷ (ωC)
1 ÷ (6,283.19 × 0.0001) = 1.5915 - 4
Net reactance X = XL − XC
62.8319 − 1.5915 = 61.2403 - 5
Impedance Z = √(R² + X²)
√(50² + 61.2403²) = 79.0593
How does this calculator work?
For a series RLC circuit at frequency f, XL = 2πfL, XC = 1/(2πfC), and total impedance Z = √(R² + (XL − XC)²). Phase angle φ = atan((XL − XC)/R): positive means inductive (current lags), negative means capacitive (current leads). At resonance XL = XC and Z = R.
Formula
How this is calculated
In an AC circuit, inductors and capacitors oppose current flow in a frequency-dependent way called reactance. The inductive reactance XL = 2πfL grows linearly with frequency — inductors block high frequencies. The capacitive reactance XC = 1/(2πfC) falls as frequency rises — capacitors block low frequencies. At resonance (f₀ = 1/(2π√(LC))) the two cancel exactly.
The total series impedance is Z = √(R² + (XL − XC)²), the Pythagorean combination of resistance and net reactance. The phase angle φ = atan((XL − XC)/R) tells you by how many degrees the current lags (positive φ, inductive) or leads (negative φ, capacitive) the voltage. When φ = 0 the circuit is purely resistive at that frequency.
The phasor diagram below shows R on the horizontal (real) axis and net reactance X on the vertical (imaginary) axis; Z is the hypotenuse. Enter L in millihenries and C in microfarads — common bench-component units — to avoid powers of ten in the input fields. For large or small values use decimal notation (e.g. 0.47 mH for 470 µH).
Frequently asked questions
Resistance dissipates energy as heat and is constant with frequency. Reactance stores and releases energy (inductors store magnetic energy; capacitors store electric energy) and varies with frequency. Both oppose current — their combination is impedance.
A negative phase angle (φ < 0) means the capacitive reactance dominates — XC > XL — so current leads voltage. A positive φ means inductive dominance: current lags voltage. At resonance φ = 0 and impedance is purely resistive (minimum).
At low frequencies XC is very large (capacitor blocks DC) and XL is small, so the circuit is capacitive. At high frequencies XL is large and XC is small, so the circuit is inductive. At the resonant frequency they cancel and Z = R (minimum for a series circuit).
Also known as
TG we-Calculate Editorial Team. (2026). RLC Impedance Calculator — Z, Phase Angle & Reactance [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/rlc-impedance-calculator
TG we-Calculate Editorial Team. "RLC Impedance Calculator — Z, Phase Angle & Reactance." TG we-Calculate. 2026. https://we-calculate.com/calculator/rlc-impedance-calculator.
TG we-Calculate Editorial Team, "RLC Impedance Calculator — Z, Phase Angle & Reactance," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/rlc-impedance-calculator
@misc{wecalculate_rlc_impedance_calculator, title = {RLC Impedance Calculator — Z, Phase Angle & Reactance}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/rlc-impedance-calculator}}, year = {2026}, note = {TG we-Calculate} }
Did this calculator help you?