# Ampere-Turn Calculator & Coil Comparison

Calculate and compare the increase or decrease in the strength of the magnetic field of a coil design simply through changing the wire diameter with the Ampere-Turn Calculator

The formula for calculating the magnetomotive force is:

$M.M.F.= NI$

Where
M.M.F. = Magnetomotive force in Ampere-Turns
N = Number of turns
I = Current in amperes (A)

If the number of turns of a coil is increased and the current remains the same, the magnetic field strength is increased. Likewise, if the current is increased and the number of turns remains the same, the magnetic field strength is increased. Reducing either the current or the number of turns will have the opposite effect.

Example 1: The M.M.F. of a 50 turn coil with 4 amperes through it is:

$M.M.F.= 50\times 4=200\; Ampere-Turn$

Example 2: The M.M.F. of a 75 turn coil with 4 amperes through it is:

$M.M.F.= 75\times 4=300\; Ampere-Turn$

Select your coil geometry, enter the dimensions, and select the units
Coil 1
Coil 2
mm
mm

### Using the Ampere-Turn Calculator to compare two coils

Coil Geometry: Select the geometry of your coil from the list. This is used to calculate the inductance and the energy stored. You can choose from single-layer solenoid, multi-layer solenoid and flat spiral coil forms

Applied Voltage: Enter the voltage that will be applied to the coil. This is used in conjunction with the resistance of the conductor in order to calculate the current

Number Of Turns: Enter the total number of turns

Coil Length: Enter the coil length, measured as depicted in the diagram above

Coil Diameter: Enter the coil diameter, measured as depicted in the diagram above

Coil Depth: Enter the winding depth, as depicted in the diagram. This does not apply to a single-layer solenoid coil

Conductor Length: This is used to calculate the resistance of the conductor

Conductor Diameter: This is used to calculate the resistance of the conductor, and provides the scaling factor for comparing against a second coil

Select Units: Select your preferred units of measurement for all the parameters

The results are calculated and updated automatically as you enter different numbers or change between the input fields. If the calculated results haven’t updated after you’ve finished entering your values, click or tap on one of the results.

Reference: Wikipedia