Magnetomotive Force Converter

Magnetomotive force (MMF) is the magnetic circuit's equivalent of electromotive force (voltage) in an electrical circuit — it's the "driving force" that pushes magnetic flux through a magnetic path such as an iron core or an air gap. Just as voltage drives current through a resistance, magnetomotive force drives magnetic flux through a magnetic reluctance, and the two circuits can be analyzed with closely parallel mathematics.

Our Magnetomotive Force converter supports the SI unit, ampere-turn (At), calculated simply as the electric current flowing through a coil multiplied by its number of turns — a coil with 50 turns carrying 4 amperes produces 200 ampere-turns of magnetomotive force. Kiloampere-turn and milliampere-turn scale this for larger or smaller values. Abampere-turn is a CGS-EMU (electromagnetic units) variant, and the gilbert (Gi) is the CGS unit of magnetomotive force, still occasionally encountered in older magnetics textbooks and specifications, particularly from European and Russian technical literature predating widespread SI adoption.

To use the converter, select your starting and target units from the dropdown lists and enter a value — the result is calculated instantly to up to 12 significant digits. For example, converting 100 ampere-turns to gilberts gives about 125.66 Gi, a conversion needed when comparing a modern coil specification to an older reference using CGS magnetics units.

Magnetomotive force calculations are essential in transformer design (determining the ampere-turns needed on primary and secondary windings), relay and solenoid engineering (calculating the coil turns and current needed to generate sufficient magnetic pull), electromagnet design (from simple demonstration magnets to industrial lifting electromagnets), and motor and generator design, where magnetomotive force from field windings establishes the working magnetic flux. Because magnetic circuits follow a relationship directly analogous to Ohm's law — magnetomotive force equals flux multiplied by reluctance, just as voltage equals current multiplied by resistance — engineers use magnetomotive force values constantly when sizing coils to achieve a target magnetic flux through a given magnetic path.

All conversion factors used in this tool are drawn from standard, internationally recognized unit definitions relating the ampere-turn and its CGS counterparts, so results are dependable for magnetics engineering, transformer and relay design, and physics coursework. The converter is free, requires no account, and works equally well on desktop and mobile devices.

Magnetomotive force divided by magnetic reluctance gives magnetic flux — so this converter pairs naturally with the Magnetic Flux converter elsewhere in this section when working through a complete magnetic circuit calculation, in the same way Ohm's law connects voltage, resistance, and current in an electrical circuit.