Inductors are essential passive components that oppose changes in alternating current (AC) by storing energy in a magnetic field. Their impedance—called reactance—depends on the inductance (L) and the operating frequency (f). Calculating this reactance in ohms is straightforward once you have the two key values.

Step 1 – Gather the Data

Locate the inductance value, expressed in henries (H) or micro‑henries (µH). This information is usually printed on the component or listed in a circuit schematic. Similarly, determine the AC frequency in hertz (Hz) from the system’s operating parameters or schematic.

Step 2 – Convert Units (if needed)

Inductors often come in micro‑henries. To work in the standard SI unit, divide the micro‑henry value by 1 000 000. For example, 10 µH becomes 10 / 1 000 000 = 0.00001 H.

Step 3 – Compute Reactance

Use the well‑known formula from electromagnetics:

$$X_L = 2\pi f L$$

Where π ≈ 3.1416. Plug in the frequency (Hz) and the inductance (H) to obtain reactance in ohms (Ω). Example: for a 10 µH inductor at 1 kHz, X_L = 2 × 3.1416 × 1 000 × 10 × 10⁻⁶ ≈ 0.063 Ω.

Knowing an inductor’s reactance helps engineers design filters, impedance matching networks, and power‑supply circuits with precision.