Find coil reactance from frequency and inductance. Add resistance to estimate impedance and phase angle. Switch units, see steps, and export clean reports fast.
Inductive reactance is the opposition a coil presents to alternating current. It rises linearly with frequency and inductance.
Outputs are shown in base units: Hz, H, and Ω. Scientific notation appears for very large or small values.
Sample values showing how XL changes with frequency and inductance.
| Frequency (Hz) | Inductance (H) | Angular Frequency ω (rad/s) | Inductive Reactance XL (Ω) |
|---|---|---|---|
| 5 | 0.1 | 314.159265 | 31.415927 |
| 6 | 0.2 | 376.991118 | 75.398224 |
| 1 | 0.01 | 6283.185307 | 62.831853 |
| 1 | 0.001 | 62831.853072 | 62.831853 |
| 1 | 0.00047 | 628318.530718 | 295.309709 |
Inductive reactance, written as XL, is the frequency‑dependent opposition an inductor presents to alternating current. It is expressed in ohms, like resistance, but it does not dissipate power as heat in an ideal coil. Instead, energy is stored in the magnetic field and returned each cycle.
The calculator uses XL = 2πfL. This relationship is linear in both frequency and inductance. Doubling frequency doubles XL; doubling inductance also doubles XL. For example, a 10 mH coil at 1 kHz gives XL ≈ 62.83 Ω.
At mains frequencies (50–60 Hz), even moderate inductances can look small: 100 mH at 50 Hz produces about 31.4 Ω. In audio (20 Hz–20 kHz), reactance varies across three decades, which is why crossover inductors are carefully selected. In RF ranges (MHz), microhenry inductors can reach hundreds of ohms.
Power chokes may be 1–100 mH, filter inductors can be 100 mH to several henries, and RF coils often sit between 10 nH and 10 µH. Using unit conversion inside the form avoids mistakes when a datasheet lists 470 µH but your design notes use millihenries.
Real coils have copper resistance. When you enter R, the tool estimates the series magnitude |Z| = √(R2 + XL2) and phase angle φ = tan-1(XL/R). If XL is much larger than R, the circuit is strongly inductive and φ approaches 90°.
A quick sensitivity check is helpful: if L has a ±10% tolerance, XL also shifts by ±10%. If frequency is controlled by a crystal oscillator, XL is stable; if it comes from an inverter, frequency drift can noticeably change reactance. The export buttons make it easy to record each scenario.
At higher frequencies, winding capacitance and core losses can dominate, so the simple model becomes approximate. Skin effect increases effective resistance, and some cores show permeability changes with temperature and flux level. Treat results as a clean baseline, then validate with measurements for critical designs.
Engineers use XL to size filters, set current ripple in converters, build impedance matching networks, and predict inrush behavior. Knowing reactance also helps interpret LCR meter readings and compare coils from different vendors. This calculator standardizes the steps so your documentation stays consistent.
Because a changing current induces a voltage across the coil. Faster changes at higher frequency require more voltage for the same current, so the apparent opposition in ohms rises.
Use the unit from your datasheet: H, mH, µH, or nH. The calculator converts everything to henries internally before computing XL in ohms.
No. Resistance dissipates energy as heat. Inductive reactance stores and returns energy each cycle in an ideal inductor, though real coils also have some resistance.
Enter R when you want an estimate of total series impedance magnitude and phase angle for an RL path, such as coil copper resistance or a deliberate series resistor.
At DC, XL = 0 because there is no changing current. The coil then behaves mainly like its winding resistance, aside from transient effects during switching.
Temperature mainly affects copper resistance, not the basic XL equation. Some core materials also vary with temperature, so measured inductance can drift in demanding environments.
Parasitic capacitance, core losses, skin effect, and instrument test conditions can shift real impedance. Use this calculator for first‑order design, then confirm with an LCR meter.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.