Magnetic Circuit (Flux & Flux Density)

Find the flux and flux density in a magnetic core from the coil turns, current and reluctance, free online.

Coil turns N

Current (A)

Core length (m)

Core area (m²)

Core relative permeability

Air gap (mm) (optional)

About this calculator

A magnetic circuit obeys Φ = NI ÷ ℛ, where NI is the magnetomotive force (ampere-turns) and ℛ the total reluctance of the core plus any air gap. Flux density B = Φ ÷ A. Watch for core saturation near 1.5–1.8 T for silicon steel.