Magnetic Field Strength Converter

Magnetic field strength (H) is the magnetizing field that currents create, before any material responds to it. Its SI unit is the ampere per meter (A/m). Inside a long coil of N turns and length l carrying a current I, H = N * I / l. The older CGS unit is the oersted (Oe), still used for magnets and magnetic materials.

How to convert A/m and oersted

Type a value into any field, and every other unit is calculated at once. One oersted is 1000 / (4 * π), about 79.58 A/m. For example, a coil of 500 turns on 0.25 m carrying 2 A:

1. In A/m:

   H = 500 * 2 / 0.25 = 4,000 A/m

2. In oersted: divide by 79.5775.

   4,000 / 79.5775 = 50.27 Oe

Common conversions

Magnetic field strength units

• Ampere per meter (A/m): Ampere per meter is the standard unit of magnetic field strength. It is the field inside a long coil with one ampere-turn for each meter of its length.
  Conversion Factor: 1 A/m = 0.001 kA/m

• Kiloampere per meter (kA/m): Kiloampere per meter is a unit of magnetic field strength representing one thousand amperes of current flowing through a one-meter-long conductor.
  Conversion Factor: 1 kA/m = 1000 A/m

• Ampere-turn per meter (AT/m): Ampere-turn per meter quantifies the magnetomotive force produced by one ampere-turn in a one-meter-long conductor. It accounts for both the current strength and the number of turns in a coil.
  Conversion Factor: 1 AT/m = 1 A/m

• Oersted (Oe): The oersted is the coherent derived unit of the auxiliary magnetic field H in the centimetre–gram–second system of units. It is equivalent to 1 dyne per maxwell.
  Conversion Factor: 1 Oe = 79.5775 A/m

Frequently asked questions

What is the difference between H and B?

H, in A/m, is the field the currents create. B, in teslas, is the flux density that results, which also depends on the material: B = μ * H. In air, 1 Oe of H gives 1 G of B. Flux density is converted in the Magnetic Flux Density Converter.