Magnetism converters
Magnetic Field Strength Converter
Convert magnetic field strength (H) units: A/m, A/cm, oersted and gilbert/cm.
Result
79.5775 A/m
1 Oe = 79.5775 A/m
All units for this value
| Unit | Symbol | Value |
|---|---|---|
| Ampere per meter | A/m | 79.5775 |
| Ampere-turn per meter | At/m | 79.5775 |
| Kiloampere per meter | kA/m | 0.0795775 |
| Ampere per centimeter | A/cm | 0.795775 |
| Ampere per millimeter | A/mm | 0.0795775 |
| Ampere-turn per inch | At/in | 2.02127 |
| Oersted | Oe | 1 |
| Milli-oersted | mOe | 1000 |
| Gilbert per centimeter | Gb/cm | 1 |
About this calculator
Magnetic field strength, denoted H, describes the intensity of a magnetizing influence at a point in space, distinct from the resulting flux density inside a material. This converter switches between SI units like ampere per meter, the CGS oersted, and gilbert-per-centimeter figures found in older references.
How it works in plain English
The converter anchors every unit to ampere per meter, the SI base unit for magnetic field strength, and rescales any entered value through that common base before expressing it in the target unit. Related SI forms such as ampere-turn per meter and kiloampere per meter follow directly from straightforward metric scaling, since a turn count multiplied by a current per length is dimensionally the same as current per length alone.
The oersted comes from the CGS system and equals 1000 divided by 4π ampere per meter, about 79.5775 A/m, the same π-based geometric factor that appears in the related magnetomotive force unit, the gilbert. Gilbert per centimeter uses the same numeric factor as the oersted because dividing a gilbert of magnetomotive force by a centimeter of path length produces a value in oersteds by definition.
Select your from and to units, enter a value, and the result appears immediately, backed by a table showing that same field strength across every supported unit. A precision control adjusts the number of decimal places shown, and a swap button flips the two selected units in a single click.
The formula
- value_in_target = value_in_source × (source factor to A/m) ÷ (target factor to A/m)
- 1 oersted (Oe) = 1000 ÷ (4π) = 79.5775 A/m
- 1 gilbert per centimeter = 79.5775 A/m
- 1 kiloampere per meter = 1000 A/m
Worked example
Suppose a magnet specification sheet lists a coercivity of 12 oersted, a common way older or CGS-based datasheets describe how resistant a material is to demagnetization, and an engineer wants that figure in ampere per meter for a modern SI-based comparison. Multiplying by the oersted factor: 12 × 79.5775 = 954.93 A/m.
Entering 12 into the oersted field with A/m selected as the target shows about 954.93 A/m right away. The full unit table also converts that same value to roughly 9.5493 A/cm and 0.95493 kA/m, all generated from the single entered figure without further calculation.
Typical magnetic field strength values
| Example | Approximate field strength |
|---|---|
| Earth's magnetic field strength (surface) | ≈0.3-0.6 A/m |
| Small permanent magnet, near surface | ≈1,000-10,000 A/m |
| Coercivity of soft magnetic iron | ≈80-800 A/m |
| Coercivity of a hard ferrite magnet | ≈150,000-300,000 A/m |
| 1 oersted | 79.5775 A/m |
Standard unit definitions and general electromagnetics references
Frequently asked questions
How is magnetic field strength H different from magnetic flux density B?
H describes the magnetizing influence applied by currents or magnets, independent of any material present, while B describes the actual resulting flux density inside a material or region, which depends on how that material responds to H. In free space the two are proportional by a fixed constant, but inside magnetic materials they can differ substantially.
Why does the oersted use a factor involving π?
The oersted is defined within the CGS electromagnetic system, which derives its magnetic units from idealized spherical geometry rather than the straight-line ampere-per-meter definition used in SI. That geometric origin is why converting between oersted and A/m requires the factor 1000 divided by 4π rather than a simple round number.
Where does the oersted still commonly appear?
Coercivity values for magnetic materials, magnetic tape and hard-disk specifications, and some geophysics literature still often quote figures in oersted, particularly in datasheets that predate wider SI adoption or that follow long-established industry convention. Converting these to A/m helps line them up with modern SI-based specifications.
Is gilbert per centimeter really the same numeric value as oersted?
Yes, in this converter both use the same conversion factor of 79.5775 A/m per unit, because a gilbert per centimeter is defined as magnetomotive force divided by a length, and the oersted turns out to equal exactly that combination by definition within the CGS system.
Can I convert directly between ampere-turn per inch and oersted?
Yes. Select ampere-turn per inch as the from unit and oersted as the to unit, then enter your value; the converter routes the calculation through the shared A/m base automatically. There is no need to manually apply the inch-to-meter and oersted conversion factors yourself.
Related converters
Convert magnetomotive force units: ampere-turns, gilberts and abampere-turns.
Convert magnetic flux units: weber, milliweber, maxwell and volt-second.
Convert magnetic flux density units: tesla, gauss, milligauss and gamma.
Convert between metric, US customary and imperial length units.