Solenoid Magnetic Field Calculator
Find the magnetic field strength (B) inside a current-carrying solenoid based on its turns, length, current, and core.
What this calculator does
A solenoid is a coil of wire that produces a fairly uniform magnetic field inside itself when current flows through it. This calculator estimates that field strength using the standard formula for an ideal (long, tightly wound) solenoid.
The formula
The magnetic field inside the solenoid is B = μ0 × μr × N × I / L, where N is the number of turns, I is the current in amps, L is the coil length in meters, μ0 is the permeability of free space (4π×10⁻⁷ T·m/A), and μr is the relative permeability of the core material (1 for air, much higher for iron or ferrite cores).
This is an idealized estimate that assumes a long, evenly wound coil with negligible end effects. Real-world coils, especially short ones or those with gaps, may show a somewhat weaker field near the ends. This tool is intended for general educational and planning purposes.