What is Inductive Reactance?

An inductor opposes changes in current. In AC circuits, this opposition is called inductive reactance (XL), measured in ohms. Unlike resistance, reactance is frequency-dependent — it increases linearly with frequency.

The Formula

XL = 2π × f × L

Where:

• f = frequency in hertz (Hz)
• L = inductance in henries (H)
• π ≈ 3.14159

How to Use This Calculator

Enter the inductance (in mH, µH, or H) and the AC frequency. The calculator returns XL in ohms and the impedance of the inductor at that frequency.

Practical Examples

Example 1: 100mH inductor at 60 Hz. XL = 2π × 60 × 0.1 = 37.7Ω.

Example 2: 10µH RF inductor at 100 MHz. XL = 2π × 100,000,000 × 0.00001 = 6,283Ω — effectively blocking high-frequency signal.

Example 3: Power supply choke, 1mH at 50Hz. XL = 2π × 50 × 0.001 = 0.314Ω — very low, passes power-line frequency easily.

Applications

Inductive reactance calculations are used in:

• LC filters: Designing cutoff frequencies for low-pass, high-pass, and band-pass filters.
• Transformers: Analysing magnetising inductance effects.
• RF chokes: Blocking RF signals while allowing DC or low-frequency current.
• Motor starting: Analysing inrush current with series inductors.
• Power factor correction: Inductors in combination with capacitors to balance reactive power.