Inductive Reactance (XL)
37.70 Ω
Result is updated automatically as you type.
The Formula & Core Concepts
Inductive reactance is the opposition to the change in current from an inductor in an AC circuit. It's calculated with a simple formula. Click on each component below to learn more about it.
XL = 2πfL
XL
Inductive Reactance
f
Frequency
L
Inductance
Interactive Visualization
Use the sliders to see how reactance changes with frequency and inductance. The values from the calculator above are used as a starting point.
Frequently Asked Questions
Both are measured in Ohms and oppose current flow, but they do so differently. Resistance dissipates energy as heat and affects both DC and AC circuits. Reactance (inductive or capacitive) stores and releases energy (in magnetic or electric fields) and only exists in AC circuits. Reactance is also frequency-dependent, while pure resistance is not.
In a DC circuit, the frequency is 0 Hz. Looking at the formula XL = 2πfL, if f=0, then XL is also 0 Ω. This means that for a steady DC current, a pure inductor behaves like a short circuit (a piece of wire with zero resistance). It only shows opposition (reactance) when the current is changing, which happens in AC circuits.
Impedance (Z) is the total opposition to current flow in an AC circuit. It's a complex value that combines both resistance (R) and total reactance (X). Total reactance is the difference between inductive reactance (XL) and capacitive reactance (XC). The formula is Z = √(R² + (XL - XC)²). If a circuit only has an inductor, its impedance is equal to its inductive reactance.
Entering Frequency and Inductance Without Unit Errors
The inductor reactance calculator evaluates the ideal AC relationship XL = 2πfL. Enter frequency f in hertz and inductance L in henries; the inductive reactance unit returned is the ohm.
- Normalize frequency: multiply kHz by
10^3and MHz by10^6before entering a value expected in Hz. - Normalize inductance: convert mH with
10^-3, µH with10^-6, and nH with10^-9when the input expects H. - Check zero inputs: at DC, where
f = 0, or whenL = 0, the ideal result is0 Ω. - Sanity-check the result: doubling either frequency or inductance must double
XL; if it changes by 1,000 times, recheck the selected unit. - Respect the model boundary: a real coil also has winding resistance, tolerance, temperature drift, and parasitic capacitance, so use this result below self-resonance and within the linear current range.
