What is remanence (Br)?
Short answer: remanence (Br) is the magnetic flux density that remains in a magnetic material after the magnetising field has been removed. It is the measure of how strongly the material stays magnetised. For neodymium, Br is between 1.17 T (N35) and 1.48 T (N52); for ferrite around 0.4 T. The higher the Br, the stronger a magnet of the same shape and size.
Remanence per material and grade
| Material / grade | Br (Tesla) | Br (Gauss) |
|---|---|---|
| Neodymium N35 | 1.17 – 1.21 T | 11,700 – 12,100 G |
| Neodymium N42 | 1.28 – 1.32 T | 12,800 – 13,200 G |
| Neodymium N48 | 1.38 – 1.42 T | 13,800 – 14,200 G |
| Neodymium N52 | 1.43 – 1.48 T | 14,300 – 14,800 G |
| Samarium cobalt | 0.9 – 1.15 T | 9,000 – 11,500 G |
| AlNiCo 5 | approx. 1.25 T | approx. 12,500 G |
| Ferrite | 0.2 – 0.45 T | 2,000 – 4,500 G |
AlNiCo has a high remanence but a low coercivity: it is easy to demagnetise. That is why AlNiCo is much weaker than neodymium in practice. So you need both Br and coercivity to assess a magnet; together they determine the energy product (BHmax).
Is remanence the same as the field at the surface?
No. Br is a material property, measured in a closed magnetic circuit. At the surface of a loose magnet you measure much less, usually 20 to 50% of Br, depending on the shape. An N52 with Br 1.45 T therefore often gives 0.3 – 0.65 T at the surface. See what are Gauss and Tesla?
Where do you see remanence?
- In the N value: a higher grade has a higher Br. See what do N35, N42, N48 and N52 mean?
- In the hysteresis curve: Br is the point where the B-H curve crosses the vertical axis (H = 0).
- With temperature: Br of neodymium drops by approx. 0.11 – 0.12% per °C. This is reversible as long as the magnet stays below its operating temperature.
Frequently asked questions
In what unit is remanence given?
In Tesla (T), milliTesla (mT) or kiloGauss (kG). 1 T = 10 kG = 10,000 G.
Does remanence have anything to do with the holding force in kg?
Indirectly. Holding force grows roughly with the square of the field, but depends mainly on size and shape. See how strong is a neodymium magnet?
Read also
Need help choosing? Use the Magnet Advisor or contact us.
