Engineering
Inductive Reactance Calculator
Calculate inductive reactance from inductance and frequency, or solve for inductance or frequency. Includes impedance form, AC current estimate, and phase behavior for a pure inductor.
Inductive reactance formula
Inductive reactance is the opposition an inductor presents to AC current. It rises as frequency rises and also rises as inductance increases.
XL = 2πfL
L = XL ÷ (2πf)
f = XL ÷ (2πL)
Pure inductor impedance:
ZL = jXL
Worked example
L = 10 mH
f = 1,000 Hz
XL = 2π × 1000 × 0.01
XL ≈ 62.83 Ω
At higher frequency, the same inductor has higher reactance. At lower frequency, it has lower reactance. This is why inductors oppose fast-changing current more strongly than slow-changing current.
Trusted references
For deeper AC circuit background, use non-competitor educational references such as All About Circuits – AC inductor circuits and All About Circuits – R, L, and C impedance.
Common questions
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Inductive reactance is the opposition an inductor presents to alternating current. It is measured in ohms.
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The formula is XL = 2πfL, where f is frequency in hertz and L is inductance in henries.
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Yes. Inductive reactance increases as frequency increases.
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The impedance of an ideal inductor is ZL = jXL, where the positive imaginary sign represents the phase shift.
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For a sinusoidal RMS voltage, use I = V ÷ XL for the ideal inductive current magnitude.
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At zero frequency, ideal inductive reactance is zero. Real inductors still have winding resistance.
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It gives ideal reactance. Real inductors also have winding resistance, core loss, parasitic capacitance, saturation current, tolerance, and self-resonance.
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The formula uses henries, but this calculator accepts nH, µH, mH, and H and converts automatically.