Tool
Transformer & Magnetic Circuit Designer
Design the winding turns and core for a transformer or inductor from classical magnetic-circuit theory — set the voltage, frequency and core, add an air gap or a flux concentrator, and see the required turns, saturation margin and flux split.
In plain terms
A transformer works by wrapping wire around a magnetic core — how many turns you need, and whether the core saturates (stops working properly), depends on the core's material, size and shape. This tool does that calculation: give it a voltage, frequency and core geometry, and it works out the minimum number of turns needed and how close that puts you to saturation. It also models an air gap and an optional 'flux concentrator' — a high-permeability path that pulls magnetic flux through itself, the same way a wire pulls electric current through the path of least resistance.
Winding & core
01 / inputTypical values for the material class, not one manufacturer's datasheet — check yours before building.
Shunt / flux concentrator
A parallel high-permeability path alongside the gap
339 turns required
Peak flux density 1.528 T — 85% of this core's saturation rating.
Design result
02 / readoutRequired turns
339
Peak flux density
1.528 T
Saturation margin
85%
Magnetizing inductance
1.93 H
Magnetizing current (RMS)
379.33 mA
Magnetizing current (peak)
536.46 mA
Peak flux
3.06 mWb
MMF (peak)
181.9 A·t
Total reluctance
59.51 kA·t/Wb
How this is built: a magnetic circuit solved exactly like an electrical one — reluctance in place of resistance, flux in place of current, magnetomotive force in place of voltage. Required turns come from Faraday's law (V = 4.44·f·N·B·Ae), rounded up to the nearest whole turn, which is why the actual peak flux density is always at or slightly under your target, never over. Series paths add reluctance directly; the gap and an optional shunt/concentrator combine as a parallel pair. The air gap includes a standard first-order fringing correction — flux bulges outward at the gap, enlarging its effective area beyond the core's own cross-section, so the gap's reluctance (and the "effective area" row below) is a little lower than a naive same-area calculation would give. That correction is only reliable for a gap that's small relative to the core's own cross-sectional width — a warning appears if your gap is large enough that this stops holding. Magnetizing current is treated as sinusoidal, valid well below saturation; real magnetizing current distorts as a core approaches Bsat. This is the analytical starting point real designs use before refining the geometry in a field solver (COMSOL, ANSYS Maxwell, etc.) — not a replacement for one.
Explore: Flux Concentrator Core Geometry Lab
A 3D exploration of open-core sensor shapes — closed ring, gap, half-core, sector — referenced against a real published paper.
Further reading
- Col. Wm. T. McLyman, Transformer and Inductor Design Handbook, CRC Press — the standard reference for exactly this kind of turns/core/saturation calculation.
- J. J. Grainger & W. D. Stevenson Jr., Power System Analysis, McGraw-Hill — transformer fundamentals and magnetic circuit basics.
- IEC 60076-1, Power transformers — Part 1: General — the standard reference for transformer design and rating conventions.