This magnetic field strength converter changes the magnetizing field H between amperes per meter, oersteds, amperes per centimeter and amperes per inch. Formula: 1 Oe = 1000/(4π) A/m ≈ 79.577471546 A/m. The SI unit is A/m. One oersted is exactly 1,000/(4π) A/m, about 79.5775 A/m, and 1 A/cm is 100 A/m.
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How to use the magnetic field strength converter
- Enter the field, for example 12 from a magnet datasheet in kOe, entered as 12,000 Oe.
- In the magnetic field strength converter, choose its unit and the target unit, such as Oe to A/m.
- Read the magnetic field strength converter result: 12,000 Oe ≈ 954,930 A/m (954.9 kA/m).
For Oe to A/m, multiply by 79.5775. For A/m to Oe, multiply by 0.0125664 (4π/1,000).
What is magnetic field strength?
Magnetic field strength (H) describes the magnetizing field produced by currents, in amperes per meter (A/m) in SI. The oersted is the older CGS unit; 1 Oe is about 79.58 A/m.
Conversion formula
The magnetic field strength converter stores every unit as a multiple of the base unit, the ampere per meter (A/m). To convert:
value in target unit = value × (factor of source unit ÷ factor of target unit)
where each factor is the size of the unit in amperes per meter.
Common magnetic field strength conversions
| From | To | 1 unit equals |
|---|---|---|
| ampere per meter (A/m) | oersted (Oe) | 0.01256637 Oe |
| oersted (Oe) | ampere per meter (A/m) | 79.57747 A/m |
| ampere per meter (A/m) | ampere per centimeter (A/cm) | 0.01 A/cm |
Magnetic field strength converter worked example
Convert 25 amperes per meter to oersteds:
- Factor of A/m = 1 A/m
- Factor of Oe = 79.577472 A/m
- 25 × 1 ÷ 79.577472 = 0.3141593 Oe
Magnetic field strength unit reference
| Unit | Symbol | Group | Equals (A/m) |
|---|---|---|---|
| Ampere per Meter | A/m | SI | 1 |
| Oersted | Oe | CGS | 79.57747155 |
| Ampere per Centimeter | A/cm | SI | 100 |
| Ampere per Inch | A/in | US/Imperial | 39.37007874 |
Reverse factors for each magnetic field strength unit
The reference table gives each unit in ampere per meters. To go the other way, divide by that factor; the list below does the division for you.
- Oersted (Oe), CGS: 1 Oe = 79.57747 A/m, so 1 A/m = 0.01256637 Oe.
- Ampere per Centimeter (A/cm), SI: 1 A/cm = 100 A/m, so 1 A/m = 0.01 A/cm.
- Ampere per Inch (A/in), US/Imperial: 1 A/in = 39.37008 A/m, so 1 A/m = 0.0254 A/in.
Coercivity: kOe and kA/m
Permanent magnet datasheets give coercivity in kOe in older or US literature and kA/m in IEC documents. Since 1 kOe = 79.5775 kA/m:
| kOe | kA/m | A/cm |
|---|---|---|
| 0.1 | 7.96 | 79.6 |
| 1 | 79.58 | 795.8 |
| 3 | 238.73 | 2,387.3 |
| 5 | 397.89 | 3,978.9 |
| 10 | 795.77 | 7,957.7 |
| 12 | 954.93 | 9,549.3 |
| 20 | 1,591.55 | 15,915.5 |
Use the same unit as the grade table you are comparing against.
H, B and coils
Inside a long solenoid, H = N × I ÷ l: 500 turns over 0.25 m carrying 2 A gives 4,000 A/m. Flux density follows B = μ₀ μᵣ H, with μ₀ ≈ 1.25663706127 × 10⁻⁶ N/A². In air, μᵣ ≈ 1, so 1 Oe of H corresponds to about 1 G (0.1 mT) of B, which is why the two CGS units were often used interchangeably. Use the magnetic flux density converter for B and the magnetomotive force converter for N × I.
Field inside a solenoid
For a long solenoid, H = N × I ÷ L. A coil of 1,000 turns carrying 0.5 A over 0.25 m gives H = 2,000 A/m. The magnetic field strength converter shows that as about 25.1 Oe, since one oersted is 1,000 ÷ 4π, or about 79.58 A/m.
For scale, Earth’s field is roughly 0.5 Oe, or about 40 A/m, at mid-latitudes. Permanent magnet coercivities are much larger: tens of kA/m for ferrites in the low end, and above 900 kA/m for strong NdFeB grades. Data sheets often give these in kOe, so 12 kOe is about 955 kA/m.
In CGS units, B in gauss and H in oersted are numerically equal in air, which is why older texts sometimes use them loosely. Inside iron they are not equal at all, so check which quantity a data sheet means before you convert. SI keeps the two clearly apart, with B in tesla and H in A/m.
Related converters and calculators
Related magnetic tools:
- Magnetic flux density converter: T and G
- Magnetomotive force converter: At and Gb
- Magnetic flux converter: Wb and Mx
- Linear current density converter: A/m
- Inductance converter: H, mH, µH
Sources
NIST CODATA: Vacuum magnetic permeability; NIST Special Publication 811, Appendix B.
Questions about this calculator
What is the SI unit of magnetic field strength?
Ampere per meter (A/m).
How do I convert Oe to A/m?
Multiply by 79.5775. For example, 50 Oe ≈ 3,978.9 A/m.
How do I convert A/m to Oe?
Multiply by 0.0125664. For example, 1,000 A/m ≈ 12.57 Oe.
How do I convert kOe to kA/m?
Multiply by 79.5775. For example, 10 kOe ≈ 795.8 kA/m.
Is an oersted the same as a gauss?
No. Oe measures H and G measures B, but in air 1 Oe corresponds to about 1 G.
Check the assumptions and units before relying on a result. Financial, tax and health estimates do not replace advice for your individual circumstances.
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