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Inductor Calculator

Coil design, impedance, and energy calculations

Inductance

30.843 µH

Mode

Coil Design

Inductance

30.843 µH

Solenoid formula: L = µ0 × N² × A / l

Example Calculations

1Air-core solenoid: 50 turns, 25mm diam, 50mm long

Inputs

Turns50
Diameter25 mm
Length50 mm

Result

Inductance48.450 µH

r = 0.0125m, A = π(0.0125)² = 4.91×10⁻⁴ m². L = 4π×10⁻⁷ × 2500 × 4.91×10⁻⁴ / 0.05 = 30.8µH.

2Impedance: 1mH at 1kHz

Inputs

Inductance1 mH (0.001 H)
Frequency1,000 Hz

Result

Reactance6.28 Ω

XL = 2π × 1000 × 0.001 = 6.28Ω.

Frequently Asked Questions

Q

How do I calculate inductance of a solenoid?

L = µ0 × N² × A / l, where µ0 = 4π×10⁻⁷ H/m, N = turns, A = cross-section area, l = coil length. A 50-turn coil, 25mm diameter, 50mm long has L ≈ 48.4µH.

  • µ0 = 4π × 10⁻⁷ H/m (permeability of free space)
  • N = number of turns
  • A = πr² (cross-section area)
  • l = coil length (winding length, not wire length)
Q

What is inductive reactance?

XL = 2πfL: the opposition to AC current by an inductor, measured in ohms. It increases with frequency—inductors block high frequencies and pass low frequencies.

  • XL = 2πfL in ohms
  • 1mH at 1kHz: XL = 6.28Ω
  • 1mH at 10kHz: XL = 62.8Ω
  • Inductor = short circuit at DC (XL = 0)
Q

How much energy does an inductor store?

E = ½LI². A 1mH inductor carrying 1A stores 0.5mJ. Energy scales with current squared—doubling current quadruples stored energy.

  • E = 0.5 × L × I²
  • 1mH at 1A = 0.5mJ
  • 1mH at 10A = 50mJ
  • Released as voltage spike when current interrupted
Q

How do I increase inductance?

More turns (L ∝ N²), larger diameter, shorter coil, or add a ferrite core (µr = 100–5000). A ferrite core boosts inductance by its relative permeability.

  • Double turns = 4x inductance (N²)
  • Larger diameter = more inductance
  • Shorter coil = more inductance
  • Ferrite core: multiply by µr (100–5000)

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Last Updated: Mar 20, 2026

This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered professional financial, medical, legal, or other advice. Always consult a qualified professional before making important decisions. UseCalcPro is not responsible for any actions taken based on calculator results.

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