Inductive Reactance Calculator
Inductive Reactance (XL)37.6991 Ω
The Inductive Reactance Calculator finds how strongly a coil opposes alternating current at a given frequency. Reactance XL rises with both frequency and inductance, which is why inductors block high-frequency signals while passing DC. Enter the operating frequency and the inductance, pick your units, and read the reactance in ohms.
Formula
XL = 2·π·f·L
- XL
- Inductive reactance in ohms
- f
- Frequency of the AC signal in hertz
- L
- Inductance in henries
How it works
- Enter the signal frequency (Hz, kHz, or MHz) and the inductance (H, mH, or µH) of the coil.
- The calculator converts both to base units and evaluates XL = 2·π·f·L.
- Because XL is directly proportional to frequency, doubling the frequency doubles the reactance; the same is true for inductance.
Worked example
A 100 mH choke operating on a 60 Hz mains supply.
- Convert: L = 100 mH = 0.1 H.
- XL = 2 × π × 60 × 0.1.
- XL = 376.991 × 0.1 ≈ 37.6991 Ω.
The reactance is about 37.6991 Ω.
Frequently asked questions
- How is inductive reactance different from resistance?
- Resistance dissipates energy as heat and is constant with frequency, while inductive reactance stores and returns energy each cycle and grows with frequency. Reactance also shifts current 90 degrees behind voltage.
- What is the reactance of an inductor at DC?
- At zero frequency (DC) the reactance is zero, so an ideal inductor behaves like a short circuit. This calculator requires a positive frequency because the formula scales with f.
- How do I combine XL with resistance to get impedance?
- For a series RL circuit the magnitude of impedance is the square root of (R squared plus XL squared). The reactance from this tool is the XL term in that calculation.