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Reactance

Calculate capacitive reactance, inductive reactance and LC resonant frequency.

Inputs

Results update as you change the inputs.

Frequency
Capacitance
Inductance

Result

Enter your values to calculate a result.

Capacitive and inductive reactance
Capacitive and inductive reactance

A capacitor and an inductor oppose alternating current in different ways. Enter the frequency and component values to find their reactance and the LC resonant frequency.

Illustration only. Not to scale.

Resonant frequency

N/A

Capacitive reactanceN/A
Inductive reactanceN/A
FrequencyN/A
PeriodN/A
Method and assumptions

Xc = 1/(2πfC), Xl = 2πfL, fres = 1/(2π√LC).

  • This assumes ideal components. ESR, ESL and parasitic capacitance are not included.
  • Reactance is shown in ohms. The sign indicates the direction of its imaginary component.

What happens at resonance

At the resonant frequency the capacitive and inductive reactances are equal in magnitude. Below resonance, the capacitor dominates. Above resonance, the inductor dominates.