Inductive Reactance Calculator
This inductive reactance calculator finds how much an inductor opposes alternating current, using the inductive reactance formula XL = 2π f L. Enter the frequency and the inductance, and the inductive reactance calculator returns the reactance in ohms and kilohms. It works for chokes, coils, transformers, and motor windings.
Results
The Inductive Reactance Calculator is part of our Electronics collection. Browse more electronics to size, convert, and check your work alongside this tool.
What the inductive reactance calculator shows
An inductor resists changes in current, so it opposes AC more strongly as the frequency rises. The inductive reactance calculator gives that opposition, XL, in ohms. It is the mirror image of a capacitor, which opposes AC less as frequency rises.
The inductive reactance formula
The inductive reactance formula is:
f is the frequency in hertz and L the inductance in henries. Reactance rises in direct proportion to both, so doubling the frequency doubles XL. At DC, XL is zero and only the wire resistance of the coil remains.
Reactance of inductor calculator example
A 100 mH inductor at 60 Hz. The reactance of inductor calculator gives:
At 6 kHz the same inductor rises to about 3,770 Ω.
How to use the inductive reactance calculator
Enter the frequency in hertz and the inductance in millihenries. The inductive reactance calculator returns XL in ohms and kilohms. Use 50 or 60 Hz for mains equipment and the signal frequency for audio and radio circuits.
Reading the inductive reactance calculator result
XL limits AC current like a resistor but stores energy in a magnetic field instead of burning it as heat. Current through an inductor lags the voltage by 90 degrees. When a coil also has resistance, combine them as Z = √(R² + XL²).
When to use the inductive reactance calculator
- Designing LC and RL filters with the inductive reactance calculator
- Sizing chokes for power supplies
- Estimating motor winding impedance
- Checking coil current at mains frequency
Common inductive reactance calculator mistakes
- Millihenries as henries. 100 mH is 0.1 H.
- Ignoring coil resistance. Add it as impedance, not directly.
- Forgetting 2π. Use angular frequency.
Tips for accurate results
- Use the real operating frequency.
- Check the inductor's current rating to avoid saturation.
- Measure inductance at the working frequency if possible.
Inductive reactance formula and resonance
Because XL rises with frequency and Xc falls, there is one frequency where they are equal and cancel. That is resonance, f = 1 / (2π√(LC)), and the LC resonance calculator finds it directly. Tuned circuits in radios use this to pick one station out of many.
Reactance of inductor calculator vs real coils
A real coil has winding resistance and some capacitance between turns, so at very high frequency it stops behaving like a pure inductor. The reactance of inductor calculator gives the ideal value; check the coil's self-resonant frequency for RF designs.
Inductive reactance formula reference at 60 Hz
| Inductance | XL at 60 Hz | XL at 50 Hz |
|---|---|---|
| 10 mH | 3.77 Ω | 3.14 Ω |
| 100 mH | 37.7 Ω | 31.4 Ω |
| 500 mH | 188.5 Ω | 157.1 Ω |
| 1 H | 377 Ω | 314 Ω |
Inductive Reactance Calculator FAQ
What is the inductive reactance formula?
XL = 2πfL, with f in hertz and L in henries.
Why does inductive reactance rise with frequency?
A faster-changing current induces a larger back voltage in the coil, so it opposes the current more.
What is XL at DC?
Zero. At DC only the resistance of the wire remains.
How is inductive reactance different from capacitive reactance?
XL rises with frequency; Xc falls with frequency. They cancel at the resonant frequency.