Solenoid Inductance Calculator

A solenoid is a coil of wire wound into a tightly packed helix. When current flows through it, it creates a magnetic field and exhibits inductance, which resists changes in current flow.

The basic formula is L = µ₀ × µᵣ × N² × A / l, where L is inductance, µ₀ is permeability of free space, µᵣ is relative permeability, N is number of turns, A is cross-sectional area, and l is coil length.

Inductance is measured in henries (H). Common subunits include millihenries (mH = 10⁻³ H) and microhenries (µH = 10⁻⁶ H). Most small coils have inductance in the µH range.

Measure coil diameter and length from center to center of the wire. For pitch measurements, measure the spacing between adjacent turns parallel to the coil axis.

Key factors include number of turns (squared relationship), coil diameter, coil length, core material permeability, and wire spacing. More turns and larger diameter increase inductance, while longer coils decrease it.

Yes, for air core coils, set the relative permeability to 1.0. Air core coils are common in RF applications and have stable inductance values regardless of current.

This calculator provides good approximation for single-layer solenoids. Accuracy decreases for multi-layer coils, very short coils, or when wire diameter approaches coil diameter.

Inductance (L) is the inherent property of the coil measured in henries. Inductive reactance (XL = 2πfL) is the AC impedance that depends on both inductance and frequency.