Inductive reactance
XL = ω * L
f = XL / (2 * π * L)
L = XL / ω
Capacitive reactance
XC = 1 / (ω * C)
f = 1 / (2 * π * C * XC)
C = 1 / (ω * XC)
Angular frequency
ω = 2 * π * f
Definitions
XL = Inductive reactance (Ω)
XC = Capacitive reactance (Ω)
L = Inductance (H)
C = Capacitance (F)
f = Frequency (Hz)
ω = Angular frequency (rad/s)
π = 3.1415926535
Calculate inductive and capacitive reactance in AC circuits.
"The opposition caused by inductance or capacitance to alternating current."
Inductive Reactance (XL): Opposition from inductors to AC current
Capacitive Reactance (XC): Opposition from capacitors to AC current
XL = 2 * π * f * L
XC = 1 / (2 * π * f * C)
Where:
XL: Inductive reactance (Ω)
XC: Capacitive reactance (Ω)
f: Frequency (Hz)
L: Inductance (H)
C: Capacitance (F)
Note: X_L increases with frequency; X_C decreases with frequency.
The opposition an inductor presents to AC current flow. Energy is stored in a magnetic field, causing current to lag voltage by 90°.
Common in motors, transformers, and chokes.
The opposition a capacitor presents to AC current flow. Energy is stored in an electric field, causing current to lead voltage by 90°.
Common in filters, power factor correction, and coupling circuits.
The number of cycles per second in an AC waveform, measured in hertz (Hz).
Standard power frequencies:
50 Hz – Used in most countries (e.g., China, Europe)
60 Hz – Used in North America, Japan
A measure of a coil's ability to store energy in a magnetic field. Unit: Henry (H).
Microhenry (μH) = 10⁻⁶ H
Millihenry (mH) = 10⁻³ H
A measure of a capacitor's ability to store charge. Unit: Farad (F).
Microfarad (μF) = 10⁻⁶ F
Nanofarad (nF) = 10⁻⁹ F
Picofarad (pF) = 10⁻¹² F
1. Designing LC filters and tuned circuits
2. Calculating resonant frequency in RLC circuits
3. Analyzing phase relationships in AC systems
4. Teaching AC circuit fundamentals
5. Troubleshooting motor or power factor issues
Inductive reactance XL is proportional to frequency and rises at higher frequency. Capacitive reactance XC is inversely proportional to frequency and falls at higher frequency.
For DC (0 Hz), XL approaches zero and XC approaches infinity.
The formulas use base units Henry (H) and Farad (F). Real‑world components are commonly rated in μH, mH, μF, nF and pF.
Always convert units correctly; wrong units will produce heavily skewed reactance results.
This calculator uses ideal‑component models and computes pure reactance only. It ignores coil DC resistance, capacitor ESR and component losses.
For practical hardware design, correct results with real‑world impedance, phase and non‑ideal device characteristics.
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