Inductive and Capacitive Reactance Calculator
Basic electronics is governed by Ohm's law, Kirchhoff's laws, and semiconductor principles. Calculations of resistance, power, voltage, and amperage form the foundation for designing and maintaining circuits. Use this calculator to determine the inductive reactance XL = 2πfL and capacitive reactance XC = 1/(2πfC) for inductors and capacitors at any frequency. Compare results and visualize the behavior. All values are current as of 2026 and are reviewed periodically to keep you up to date.
When to use this calculator
- Circuit design and analysis involving inductive (XL) and capacitive (XC) reactance
- Validate theoretical calculations before building circuits
- Teaching basic and advanced electronics
- Estimate parameters for microcontroller projects (Arduino, ESP32, STM32)
- Troubleshooting existing circuits
L=10 mH, C=1 µF, f=1 kHz
- XL = 2π × 1000 × 0.01 = 62.8 Ω
- XC = 1/(2π × 1000 × 1e-6) = 159 Ω
- At this frequency, the capacitor blocks more than the inductor
How it works
1 min readElectronics is governed by Ohm's law, Kirchhoff's laws, and Faraday's law. Applying the correct formulas prevents costly errors and electrical failures.
How It's Calculated
Inductive reactance XL represents the opposition to current change in an inductor, while capacitive reactance XC represents the opposition to voltage change in a capacitor. Both depend on frequency:
This calculator applies these formulas with your input values, checking typical ranges and alerting you to values outside normal bounds.
Final Notes
This calculation is a reference guide. For critical decisions (electrical design, safety-critical systems), consult a qualified electrical engineer. Values are current as of 2026 and are reviewed periodically.
Frequently asked questions
What is the difference between reactance and resistance?
Resistance dissipates energy as heat. Reactance stores energy in a magnetic field (inductor) or electric field (capacitor). Reactance does not dissipate—it returns energy each cycle.
What is XL at DC (0 Hz)?
XL is zero at DC, acting as a short circuit. A stable DC inductor exhibits only the resistance of its wire.
What is XC at DC (0 Hz)?
XC is infinite at DC, acting as an open circuit. The capacitor charges and blocks direct current.
Is reactance the same as impedance?
No. Impedance Z = R + jX (resistance + complex reactance). For a pure inductor: Z = jXL. For a pure capacitor: Z = −jXC.
Why does phase shift occur in AC circuits?
In inductors, current lags voltage by 90°. In capacitors, current leads voltage by 90°. This occurs because energy oscillates cyclically instead of being dissipated.
What happens when XL equals XC (resonance)?
At resonance, XL and XC are equal in magnitude but opposite in sign, so they cancel. In a series circuit, impedance becomes purely resistive. In a parallel circuit, impedance becomes very high.
How do I measure reactance in practice?
Use an RLC meter, or measure voltage and current with an oscilloscope at a known frequency, then calculate Z = V/I and derive reactance from Z.
Is this calculator free?
Yes, all our calculators are free and require no registration.