Reactance & Impedance Calculator

Compute inductive and capacitive reactance at a given frequency and combine them with resistance into total impedance and phase angle. Calculates in your browser.

Capacitive reactance Xc-
Inductive reactance Xl-
Net reactance X-
Impedance |Z|-
Phase angle-

Show the math

Reactance depends on frequency; impedance combines it with resistance:

Xc = 1 ÷ (2πfC)  ·  Xl = 2πfL

|Z| = √(R² + (Xl − Xc)²)

A positive phase angle is inductive, negative is capacitive. Leave a field blank or zero to omit that component. All math runs in your browser.

What this does

A reactance & impedance calculator computes inductive and capacitive reactance at a given frequency and combines them with resistance into total impedance and phase angle.

How to use it

  1. Enter the frequency.
  2. Enter inductance and capacitance.
  3. Enter the resistance.
  4. Read the reactances, impedance, and phase.

How it works

Reactance is the frequency-dependent opposition of inductors and capacitors. The phase angle is arctan((XL − Xc) ÷ R).

XL = 2πfL; Xc = 1 ÷ (2πfC); Z = √(R² + (XL − Xc)²)

Understanding your result

The key insight is that reactance changes with frequency: an inductor opposes high frequencies more, a capacitor less, so impedance and the phase angle shift across the band. The phase angle tells you whether the circuit looks inductive or capacitive overall, and at the frequency where the two reactances cancel you hit resonance, where impedance is purely resistive.

Example

At 1 kHz, a 10 mH inductor has about 63 Ω of reactance.

Sources & methodology

Last updated .

Frequently asked questions

How are reactances calculated?

Inductive reactance is XL = 2πfL and capacitive reactance is Xc = 1 ÷ (2πfC), both in ohms at frequency f.

How does impedance combine them?

Impedance magnitude is Z = √(R² + (XL − Xc)²), and the phase angle is arctan((XL − Xc) ÷ R).

Is my data stored?

No. Everything is calculated locally in your browser.