Magnetomotive Force Converter — Ampere-Turn & Gilbert
Convert magnetomotive force (MMF) between different units including ampere-turn, gilbert, kiloampere-turn, and more. Essential for transformer design, electromagnet calculations, and magnetic circuit analysis. See also our Magnetic Field Strength Converter and Inductance Converter.
Value:
How to Convert Magnetomotive Force
- Enter the magnetomotive force value in the input field above.
- Select the unit you are converting from in the "From" dropdown menu.
- Select the unit you want to convert to in the "To" dropdown menu.
- The result will automatically appear in the result field.
- Use the copy button to copy the result to your clipboard.
- Click any conversion in the list below to quickly select those units.
Magnetomotive Force Formula
Magnetomotive Force Definition:
MMF = N × I
Where:
MMF = Magnetomotive force (ampere-turns)
N = Number of turns (dimensionless)
I = Current (amperes)
Unit Conversion:
1 ampere-turn (At) = 1.25664 gilbert (Gi)
1 gilbert (Gi) = 0.795775 ampere-turn (At)
1 gilbert = 10/(4π) ampere-turns
Magnetic Circuit (Hopkinson's Law):
MMF = Φ × R
Where: Φ = magnetic flux (Wb), R = reluctance (A/Wb)
Relationship to H-field:
MMF = ∮H⋅dl = NI
H = NI/L (for solenoid)
Common Units:
SI: ampere-turn (At), kiloampere-turn (kAt)
CGS: gilbert (Gi) = 10/(4π) At ≈ 0.7958 AtExample Conversion
Problem: A coil has 500 turns carrying 2A. Convert the MMF to gilberts.
Given: N = 500, I = 2A, so MMF = 500 × 2 = 1000 At
Solution:
• To gilbert: 1000 At × (1 Gi / 0.795775 At) = 1000 / 0.795775 = 1256.64 Gi
Answer: 1000 At = 1256.64 Gi = 1 kAt
Technical Details
Magnetomotive force (MMF) is the driving force that establishes magnetic flux in a magnetic circuit, analogous to electromotive force (EMF) in an electric circuit. It is produced by current flowing through a coil and equals the product of current and number of turns (NI). MMF drives magnetic flux through the reluctance of the magnetic path.
In transformer and inductor design, MMF determines the magnetic flux density in the core. Typical values range from a few ampere-turns (small signal inductors) to thousands of ampere-turns (power transformers and electromagnets). The gilbert, named after William Gilbert, is the CGS unit still used in some magnetic recording and materials specifications.
Magnetomotive Force Reference Table
| Application | Typical MMF | Description |
|---|---|---|
| Small signal inductors | 1-100 At | Audio and RF circuits |
| Relay coils | 50-500 At | Electromagnetic switches |
| Solenoid valves | 100-2000 At | Fluid control actuators |
| Power transformers | 500-10,000 At | Electrical power conversion |
| Electric motors | 1,000-50,000 At | Stator and rotor windings |
| MRI magnets | 10⁵-10⁶ At | Medical imaging superconducting coils |
| Electromagnets (industrial) | 10³-10⁵ At | Lifting and holding magnets |
| Magnetic recording heads | 0.1-10 At | Data storage write heads |
Frequently Asked Questions
What is magnetomotive force?
Magnetomotive force (MMF) is the force that drives magnetic flux through a magnetic circuit. It equals the product of current and number of coil turns (NI) and is measured in ampere-turns (At). It is analogous to voltage (EMF) in electric circuits.
What is the difference between ampere-turn and gilbert?
Both measure MMF. The ampere-turn (At) is the SI unit, while the gilbert (Gi) is the CGS unit. 1 At = 4π/10 Gi ≈ 1.2566 Gi, or equivalently 1 Gi ≈ 0.7958 At. The gilbert is named after William Gilbert, pioneer of magnetism research.
How is MMF related to magnetic flux?
MMF drives magnetic flux through reluctance: Φ = MMF/R (Hopkinson's law), analogous to I = V/R in electric circuits. Higher MMF produces more flux, while higher reluctance (longer path, smaller area, lower permeability) reduces flux.
How do you increase MMF in a coil?
MMF = NI, so you can increase it by adding more turns (N) or increasing current (I). Doubling turns at the same current doubles MMF. In practice, more turns increase resistance and inductance, so design involves trade-offs between MMF, size, and losses.
What is Hopkinson's law?
Hopkinson's law states MMF = Φ × R, where Φ is magnetic flux and R is reluctance. It is the magnetic circuit equivalent of Ohm's law (V = IR). Reluctance R = L/(μA) depends on path length L, permeability μ, and cross-sectional area A.
Objective of Measurement:
Measurement is the most important aspect of our life. We use measurement in science, engineering, business trading, personal life, education, and more other fields. As technology is growing day by day so we need a highly accurate and easy convenient global measuring system in each and every field. It is essential to use standard measurement in every field that everyone to be sure that they not get cheated.
History of Measurement:
In history for measurement people used the human body as a tool. For measuring length used forearm, hand, foot & finger as a unit. The foot, finger is a subdivided shorter unit of a length. This type of measurement is not accurate cause different in size of the arm & finger for different people & some of the countries still using it. In history, there were lots of measuring systems developed but mostly used imperial, the metric system of measurement. We use these systems for measure distances, volume, weight, speed, area etc. Due to this a major problem everyone is facing while doing trading between the countries. A huge improvement in civilization, It necessary to improve measuring standards. Nowadays International Standard (SI) units are used as a global measurement system.
Magnetomotive Force Conversion - Unit Converter:
Our magnetomotive force conversion converter convert ampere-turn [At], kiloampere-turn [kAt], milliampere-turn [mAt], ampere [A], gilbert [Gi], kilogilbert [kGi], milligilbert [mGi], microampere-turn [μAt], abampere-turn [abAt], statampere-turn [statAt] vice versa with metric conversion.
Magnetomotive force conversions & its abbreviations
| Unit | Abbreviation | Unit | Abbreviation |
|---|---|---|---|
| ampere-turn | At | kiloampere-turn | kAt |
| milliampere-turn | mAt | ampere | A |
| gilbert | Gi | kilogilbert | kGi |
| milligilbert | mGi | microampere-turn | μAt |
| abampere-turn | abAt | statampere-turn | statAt |
Complete list of Magnetomotive force conversion units and its conversion.
1 ampere-turn [At] = 1.25664 gilbert [Gi]
1 gilbert [Gi] = 0.795775 ampere-turn [At]
1 ampere-turn [At] = 0.001 kiloampere-turn [kAt]
1 kiloampere-turn [kAt] = 1000 ampere-turn [At]
1 ampere-turn [At] = 1000 milliampere-turn [mAt]
1 milliampere-turn [mAt] = 0.001 ampere-turn [At]
1 ampere-turn [At] = 0.1 abampere-turn [abAt]
1 abampere-turn [abAt] = 10 ampere-turn [At]