🌀 Inductance: Calculator

Calculate inductive reactance, or estimate a solenoid coil's inductance from its geometry.

Hz
INDUCTIVE REACTANCE
0 Ω
Enter values to see the calculation.

How the Inductance Calculator Works

This calculator covers two related electronics calculations. Inductive Reactance tells you how much an inductor resists changes in AC current at a given frequency (measured in ohms, just like resistance). Solenoid Inductance estimates the inductance of a simple air-core coil based on its physical geometry — the number of turns, its cross-sectional area, and its length.

Inductive Reactance: XL = 2π × f × L
Solenoid Inductance: L = (μ₀ × N² × A) ÷ l  (μ₀ = 4π×10⁻⁷ H/m)

Why Inductive Reactance Increases With Frequency

Unlike a resistor, an inductor's opposition to current flow isn't constant — it grows directly with frequency. At low frequencies (like 60Hz household AC), a small inductor has very little reactance, but the same inductor at radio frequencies (megahertz range) can have enormous reactance, which is why inductors are used as frequency-selective components in filters and radio circuits.

Limitations of the Solenoid Formula

The solenoid inductance formula used here assumes a simple, tightly-wound air-core coil where the length is significantly greater than the coil's radius. Real-world coils with a magnetic core material (like iron or ferrite) will have significantly higher inductance than this air-core estimate, since core material permeability isn't included in this simplified formula.

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❓ Frequently Asked Questions

What is inductive reactance?
Inductive reactance (X_L) is the opposition an inductor presents to alternating current, measured in ohms. Unlike plain resistance, it depends on the AC frequency — reactance increases as frequency increases, following X_L = 2πfL.
What is the difference between inductance and inductive reactance?
Inductance (L, measured in henries) is a fixed physical property of a coil based on its construction. Inductive reactance (X_L, measured in ohms) is the frequency-dependent opposition to current that results from that inductance at a specific AC frequency.
Does the solenoid formula work for coils with an iron core?
No, not accurately. This formula assumes an air core (relative permeability of 1). An iron or ferrite core dramatically increases inductance — often by a factor of hundreds or thousands — because of the core material's much higher magnetic permeability.
Why do inductors act as filters in circuits?
Because their reactance increases with frequency, inductors naturally pass low-frequency signals more easily than high-frequency ones, which is why they're used in low-pass filters — the opposite behavior of a capacitor.
What units should I use for the solenoid inductance calculation?
Enter the coil's cross-sectional area in square centimeters and its length in centimeters — the calculator automatically converts these to square meters and meters for the underlying formula.

🏆 About This Tool — Accuracy & Trust

🔒 Data Privacy: All calculations run entirely within your browser using JavaScript. Nothing you enter here is ever transmitted to our servers, stored, sold, or shared.

📐 Accuracy Note: This tool uses standard, widely published formulas and guidelines. Results are estimates for informational purposes; for financial, medical, or engineering decisions, consult a licensed professional.

📅 Last Updated: September 2026.