Electronics · AC
Inductive reactance calculator.
Enter a frequency and an inductance to get the inductor’s opposition to AC, in ohms.
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Inductive reactance formula
Inductive reactance is XL = 2π × f × L, in ohms when f is in hertz and L is in henries. It rises with frequency and with inductance, so an inductor passes low frequencies and opposes high ones. At DC it is zero for an ideal inductor.
Worked example. 10 mH at 1 kHz: XL = 2π × 1,000 × 0.01 = 62.83 Ω.
Real inductors also have winding resistance, self-resonance and core saturation, so this ideal figure holds only well below the part’s self-resonant frequency.
Frequently asked questions
What is the formula for inductive reactance?
XL = 2πfL. With f in Hz and L in henries, XL is in ohms.
What is the reactance of 10 mH at 1 kHz?
About 62.83 ohms.
Why does an inductor block high frequencies?
A changing current induces a voltage that opposes the change, and faster changes produce a larger opposing voltage.
What is inductive reactance at DC?
Zero for an ideal inductor. A real one still has its winding resistance.
Does reactance depend on the current?
Not for an ideal inductor. Real cores can saturate at high current, which this calculator does not model.
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Scope and safety
Low-voltage hobby and study use only. Results are ideal-component arithmetic from the formulas shown, not an engineering design or professional advice. Real parts vary with tolerance, temperature and age, so check the datasheet for every part. Never work on mains-powered circuits from a calculator result, and discharge large capacitors safely before handling.