Inductive Reactance Calculator

Inductive Reactance Calculator. Inductors resist the flow of alternating current — and the amount of that resistance changes with frequency. The Inductive Reactance Calculator lets you enter an inductance value (L) and an AC frequency (f), selecting your preferred units for each (H, mH, µH, nH, or pH; Hz through THz), to calculate the Inductive Reactance (XL) in ohms. Secondary outputs include admittance (BL) in siemens, plus your converted inductance and frequency in base units. Also try the find Inductance with Air Core Inductor Calculator.

Results

Inductive Reactance (XL)

Admittance (BL)

Inductance (converted)

Frequency (converted)

What is inductive reactance?

Inductive reactance (XL) is the opposition an inductor presents to alternating current (AC). Unlike resistive opposition, inductive reactance does not dissipate energy as heat — instead, the inductor stores energy in its magnetic field and releases it back into the circuit. It is measured in ohms (Ω), just like resistance.

How do I calculate inductive reactance?

Inductive reactance is calculated using the formula XL = 2πfL, where f is the frequency of the AC signal in hertz and L is the inductance in henries. For example, a 100 mH inductor at 60 Hz has a reactance of XL = 2π × 60 × 0.1 ≈ 37.70 Ω.

What is the SI unit of inductive reactance?

The SI unit of inductive reactance is the ohm (Ω), the same unit used for electrical resistance. This makes sense because both resistance and reactance represent opposition to electric current flow, and both appear in impedance calculations.

What is the inductive reactance in a DC circuit?

In a DC circuit, the frequency is zero (f = 0 Hz). Plugging this into the formula XL = 2πfL gives XL = 0, meaning an ideal inductor offers no reactance to direct current. In practice, a real inductor still has a small DC resistance (DCR) due to the wire it's wound from.

What is the difference between inductive reactance and capacitive reactance?

Inductive reactance (XL = 2πfL) increases with frequency, meaning inductors resist high-frequency signals more. Capacitive reactance (XC = 1 / 2πfC) decreases with frequency, meaning capacitors pass high-frequency signals more easily. In a circuit, they oppose each other — at resonance, XL equals XC and they cancel out.

How do I calculate inductance from reactance?

Rearranging the formula XL = 2πfL, you get L = XL / (2πf). So if you know the inductive reactance in ohms and the frequency in hertz, divide the reactance by 2π times the frequency to find the inductance in henries.

What is admittance, and how does it relate to inductive reactance?

Admittance (BL) is the reciprocal of reactance — it measures how easily AC current flows through the inductor. It is calculated as BL = 1 / XL and is expressed in siemens (S). A high reactance means low admittance, and vice versa.

How does inductive reactance relate to impedance?

Impedance (Z) is the total opposition a circuit presents to AC, combining both resistance (R) and reactance (XL or XC). For a purely inductive circuit with no resistance, the impedance equals the inductive reactance: Z = XL. In real circuits with both resistance and inductance, Z = √(R² + XL²).