How this calculator works
An ideal inductor creates a voltage proportional to the current rate of change. Its sinusoidal reactance magnitude therefore increases with frequency and inductance. Complex impedance is jXL, and complex admittance is -j/XL, so inductive susceptance is negative. Winding resistance, magnetic losses, saturation and parasitic capacitance are excluded. The inverse susceptance is undefined for zero reactance, so frequency and inductance must be positive.
Formula
XL = 2 pi f L. BL = -1/XL. L = XL/(2 pi f), f = XL/(2 pi L), and XL = -1/BL.
Worked example
An inductance of 0.1 H at 50 Hz gives XL = 31.41593 ohm and BL = -0.03183099 S. A reactance of 62.83185 ohm at 100 Hz implies L = 0.1 H.
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Frequently asked questions
Why is susceptance negative?
Admittance is the reciprocal of impedance. The reciprocal of jXL is -j/XL.
Is reactance the winding resistance?
No. Reactance stores and returns energy; winding resistance dissipates heat.
What about DC?
An ideal inductor has zero steady DC reactance, but its susceptance is unbounded. This calculator returns finite AC quantities.