Inductive Reactance Calculator

Step-by-Step Guide

1. 1Enter Frequency: Input the AC signal frequency, choosing Hz, kHz, or MHz.
2. 2Enter Inductance: Input the inductor's value, choosing H, mH, µH, or nH.
3. 3Read the Inductive Reactance: View XL in ohms, calculated instantly using XL = 2πfL.
4. 4Review the Step-by-Step Derivation: See the full calculation broken into each substitution step.
5. 5Apply a Preset: Use a built-in preset spanning power-line frequencies through RF frequencies to explore how reactance scales.

What This Calculator Provides

• ✓Real-time calculation as you type
• ✓Full unit support: Hz/kHz/MHz, H/mH/µH/nH
• ✓Complete step-by-step derivation
• ✓Six built-in presets (50Hz to 1MHz)
• ✓Calculation history
• ✓Export calculation as a text file
• ✓Private: your inputs are not collected or stored
• ✓No signup required

Pro Tips

• 💡Remember that reactance scales linearly with both frequency and inductance — doubling either one doubles XL, unlike inductance itself, which scales with turns squared in the underlying coil.
• 💡Use the built-in presets to quickly get a feel for typical XL magnitudes across frequency bands — mains chokes, audio crossovers, and RF chokes all operate in very different reactance ranges for very different component values.
• 💡When comparing an inductor's reactance to a capacitor's reactance for a filter or resonance calculation, always compute both at the same frequency — reactance is meaningless to compare unless the frequency is held constant.
• 💡For a quick real-world impedance check, remember that a real inductor's total impedance also includes its winding resistance (DCR) — XL alone describes only the ideal reactive component, not the full impedance magnitude.
• 💡When sizing a choke for a switching power supply, calculate XL at the actual switching frequency, not at the AC mains frequency — inductors intended for high-frequency ripple filtering behave very differently than 50/60Hz mains chokes.

Common Mistakes to Avoid

• ✕Forgetting the 2π factor and using XL = fL instead of XL = 2πfL. This understates reactance by a factor of roughly 6.28, a common shortcut error when working quickly by hand.
• ✕Mixing up frequency unit prefixes, especially Hz and kHz. Entering 60 intending Hz but leaving the unit on kHz overstates reactance by a factor of 1,000 — always confirm the unit dropdown matches your intended frequency.
• ✕Assuming XL alone represents a real inductor's total impedance. Real components also have winding resistance and, at high frequencies, parasitic capacitance — XL is only the ideal reactive component of a more complete impedance model.
• ✕Treating inductive reactance as if it behaved like resistance in terms of power dissipation. An ideal inductor's reactance opposes current without dissipating real power as heat — power is only dissipated in the winding's actual resistance, not in the reactance itself.
• ✕Using the wrong inductance value when a coil's inductance changes with frequency, as happens with ferrite-core inductors near saturation or self-resonance. This formula assumes a fixed, ideal inductance — real component datasheets often specify inductance at a particular test frequency for this reason.