Inductive reactance
X_L = 2πfL
The magnitude of ideal inductor impedance grows linearly with frequency and inductance.
Inductive Reactance Calculator
Calculate ideal inductor reactance and AC current from inductance, frequency, and RMS voltage.
Access: Free to use, no installation, and No account required.
Inputs
This ideal model excludes winding resistance, core losses, self-resonance, parasitic capacitance, saturation, and frequency-dependent inductance.
Results
Inductive reactance
For an ideal inductor, XL = 2πfL. Increasing frequency or inductance increases opposition to sinusoidal AC current.
Engineering reference
Inductive Reactance Calculator: background and worked detail
Use the Inductive Reactance Calculator to calculate ideal inductive reactance, RMS current, reactive power, angular frequency, and peak flux linkage from inductance, frequency, and RMS voltage.
Equations used by this calculator
RMS current
I = V_RMS / X_L
For an ideal inductor, current magnitude follows Ohm's law using reactance.
Reactive power
Q = V_RMS I_RMS
An ideal inductor exchanges reactive energy with the source without average real power loss.
10 mH at 1 kHz with 10 V RMS
Use L = 10 mH, f = 1,000 Hz, and V = 10 V RMS.
- X_L = 2π × 1,000 × 0.010 ≈ 62.8 Ω.
- I_RMS ≈ 10/62.8 = 0.159 A.
- Reactive power is about 1.59 VAR.
Result: The corresponding angular frequency is about 6.28 krad/s.
Frequency-dependent opposition to current
For a sinusoidal steady state, an ideal inductor has impedance jωL, so its reactance increases linearly with both frequency and inductance. Current lags voltage by 90° in the ideal lossless model.
Real inductors also have winding resistance, core loss, parasitic capacitance, saturation, current rating, skin/proximity effects, and a finite self-resonant frequency.
Validation checks
Frequency scaling
Case: Double frequency with L and V fixed.
Expected: Reactance should double and current should halve.
Inductance scaling
Case: Double inductance with f and V fixed.
Expected: Reactance should double and current should halve.
Assumptions and model boundaries
Assumptions
- An ideal linear inductor in sinusoidal steady state.
- Inductance is constant and independent of current and frequency.
- Input voltage is RMS magnitude.
Limitations
- Does not model winding resistance, core loss, saturation, self-resonance, parasitic capacitance, or nonlinear magnetic behavior.
- At very low frequency, winding resistance may dominate the real component behavior.
Inductive Reactance Calculator FAQ
Why does an inductor oppose higher-frequency AC more strongly?
Because v = L di/dt; faster current variation requires more voltage, which appears as larger reactance X_L = 2πfL.
Does an ideal inductor consume real power?
No average real power in the ideal sinusoidal model. Real inductors do consume power through winding and core losses.
Can I use this above the inductor's self-resonant frequency?
No. Above self resonance, parasitic capacitance changes the component behavior and the simple X_L model is no longer sufficient.
Where this calculation comes from
Shared with the AC Circuits Workbench, which handles complex impedance and phasor analysis.
Open the source workbench →Read calculation and source methodology →