Magnetic Field Strength Converter

Magnetic field strength (the H field) measures the magnetizing force applied to a region of space, independent of whatever material happens to be present there. It's a subtly different quantity from magnetic flux density (the B field): field strength describes the "cause" — the magnetizing influence from a current or magnet — while flux density describes the "effect" it produces within a specific material.

Our Magnetic Field Strength converter supports the SI unit, ampere/meter (A/m), along with ampere turn/meter (numerically identical to A/m, since a "turn" is dimensionless) and kiloampere/meter for larger field strengths. The oersted (Oe) is the CGS unit, and remains in wide use for one specific purpose: rating the coercivity of permanent magnets — how resistant a magnet is to being demagnetized by an opposing field, a specification almost always still quoted in oersted even in otherwise SI-based datasheets.

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 a neodymium magnet's typical coercivity of 11,000 Oe to amperes/meter gives about 875,352 A/m, a conversion frequently needed when comparing magnet datasheets that mix CGS coercivity ratings with SI-based design calculations.

Magnetic field strength conversions matter across permanent magnet selection and design (comparing coercivity ratings between magnet grades and manufacturers), electromagnet and solenoid engineering (calculating the field strength a given coil and current will produce), magnetic recording media (the field strength needed to write or erase magnetic storage), and MRI and scientific instrumentation, where precise field strength control is essential for accurate imaging and measurement. In free space (vacuum or air), 1 oersted of field strength produces exactly 1 gauss of flux density, a simple relationship that becomes more complex inside magnetic materials with higher permeability.

All conversion factors used in this tool are drawn from standard, internationally recognized unit definitions relating the SI ampere/meter and CGS oersted, so results are dependable for magnetics engineering, permanent magnet specification, and physics coursework. The converter is free, requires no account, and works equally well on desktop and mobile devices.

Magnetic field strength is also directly related to magnetic flux density elsewhere in this section — multiplying field strength by a material's permeability gives the resulting flux density, a relationship engineers use constantly when predicting how a given coil or magnet will actually perform inside a specific magnetic material.