Reactance & Impedance Calculator
For a series RLC circuit, enter the frequency f, resistance R, inductance L, and capacitance C to get the inductive reactance XL = 2πfL, the capacitive reactance XC = 1/(2πfC), the net reactance X = XL − XC, the impedance magnitude |Z| = √(R² + X²), and the phase angle φ = atan2(X, R) (positive means the current lags the voltage — the circuit is inductive; negative means it leads — capacitive). At the resonant frequency f0 = 1/(2π√(LC)) the two reactances cancel (XL = XC) and |Z| = R, purely resistive. Also shows the quality factor Q = (1/R)√(L/C) and bandwidth BW = f0/Q. Everything runs locally in your browser.
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Tip: enter L in henries and C in farads. For a 10 mH inductor type 0.01; for a 1 µF capacitor type 0.000001.
Result
Series RLC values at this frequency
The math. Inductors and capacitors oppose AC current but, unlike a resistor, store and release energy each cycle rather than dissipating it — this "opposition without loss" is reactance, measured in ohms. The inductive reactance XL = 2πfL grows with frequency (an inductor blocks high frequencies), while the capacitive reactance XC = 1/(2πfC) falls with frequency (a capacitor blocks low/DC and passes high frequencies). In a series RLC circuit they oppose each other 180° apart, so the net reactance is X = XL − XC: positive means inductive, negative means capacitive. The total opposition is the impedance |Z| = √(R² + X²) — a Pythagorean combination of the resistive (real) and reactive (imaginary) parts, written in complex form as Z = R + jX. The phase angle φ = atan2(X, R) is how far the current is shifted from the voltage: at resonance it is 0 (current and voltage in phase, |Z| = R), and far from resonance it approaches ±90°. The resonant frequency where XL = XC is f0 = 1/(2π√(LC)). The quality factor Q = (1/R)√(L/C) measures how sharply peaked the resonance is — the bandwidth between the half-power points is BW = f0/Q. A high-Q circuit rings narrowly; a low-Q one is broad and damped. Pairs with the LC Resonant Frequency, Ohm's Law, Voltage Divider, and PWM Duty Cycle tools. Everything runs locally — nothing leaves your browser.