What do N35, N42, N48, and N52 mean?
Short answer: N35, N42, N48 and N52 are grades of neodymium magnets. The number is the maximum energy product (BHmax) of the material in MGOe: at the same size, an N52 can deliver more magnetic energy than an N35. In practice an N52 is about 20 to 40% stronger than an N35 of the same size, but less resistant to heat. The size of the magnet usually has more influence on holding force than the grade.
What do the N and the number mean?
The N stands for neodymium (NdFeB, an alloy of neodymium, iron and boron). The number is the maximum energy product BHmax, expressed in MGOe (mega-gauss-oersted). An N42 therefore has a BHmax of about 42 MGOe, or approximately 334 kJ/m³. Read more about this unit in what does BHmax mean?
Key figures per grade
| Grade | Remanence Br | BHmax | Coercivity Hcj (min.) | Max. operating temperature* |
|---|---|---|---|---|
| N35 | 1.17 – 1.21 T | 33 – 36 MGOe (263 – 287 kJ/m³) | 955 kA/m (12 kOe) | 80 °C |
| N38 | 1.21 – 1.25 T | 36 – 39 MGOe (287 – 310 kJ/m³) | 955 kA/m (12 kOe) | 80 °C |
| N42 | 1.28 – 1.32 T | 40 – 43 MGOe (318 – 342 kJ/m³) | 955 kA/m (12 kOe) | 80 °C |
| N45 | 1.32 – 1.38 T | 43 – 46 MGOe (342 – 366 kJ/m³) | 955 kA/m (12 kOe) | 80 °C |
| N48 | 1.38 – 1.42 T | 46 – 49 MGOe (366 – 390 kJ/m³) | 955 kA/m (12 kOe) | 80 °C |
| N50 | 1.40 – 1.45 T | 47 – 51 MGOe (374 – 406 kJ/m³) | 876 kA/m (11 kOe) | 60 – 70 °C |
| N52 | 1.43 – 1.48 T | 49 – 53 MGOe (390 – 422 kJ/m³) | 876 kA/m (11 kOe) | 60 – 70 °C |
*Typical values for sintered NdFeB according to common factory specifications. The actual temperature limit also depends on the shape: a thin, flat magnet loses strength sooner than a thick one. Read more in what happens to a magnet at high temperatures?
How much stronger is N52 than N35? Our figures
We stock a few magnets in several grades. The stated holding force shows how big the difference is in practice:
| Magnet | Lower grade | Higher grade | Difference |
|---|---|---|---|
| Disc Ø20 x 5 mm | N35: 3.5 kg | N48: 4.9 kg | +40% |
| Disc Ø3 x 2 mm | N35: 0.25 kg | N52: 0.39 kg | +56% |
| Cube 3 x 3 x 3 mm | N35: 0.38 kg | N50: 0.56 kg | +47% |
| Disc Ø10 x 5 mm | N48: 3.1 kg | N52: 3.3 kg | +6% |
| Disc Ø8 x 2 mm | N48: 0.79 kg | N52: 0.86 kg | +9% |
So from N48 to N52 you only gain 5 to 10%. For comparison: a Ø20 mm disc magnet in grade N48 holds approx. 0.95 kg at 2 mm thickness, approx. 4.9 kg at 5 mm and approx. 12 kg at 10 mm. A thicker or larger magnet gives much more extra strength than a higher grade.
What do the letters after the number mean (M, H, SH, UH, EH)?
A letter after the number, such as N42SH, indicates the temperature class. It is not about extra strength, but about how hot the magnet may get without permanent loss of strength:
| Suffix | Max. operating temperature (indicative) |
|---|---|
| none (N) | 80 °C |
| M | 100 °C |
| H | 120 °C |
| SH | 150 °C |
| UH | 180 °C |
| EH | 200 °C |
| AH | 220 – 230 °C |
A higher temperature class has a higher coercivity (resistance to demagnetisation). More on this in what is coercivity (Hc)?
Which grade should you choose?
- N35 to N42: fine for hobbies, crafts, sew-in magnets and applications where space is not an issue. Often the cheapest per kilo of holding force.
- N45 to N48: the best all-round choice; most of our range is N45 or N48.
- N50 to N52: when space is limited and you want the most out of a small magnet, for example in model making or 3D prints. Do not use above approx. 60 °C.
- H, SH or higher: where there is heat, such as in motors, lighting or a machine.
Unsure about the size? See which disc magnet should you choose? or which block magnet should you choose?
Frequently asked questions
Is N52 the strongest neodymium magnet?
N52 is the highest standard grade widely available. N54 and N55 also exist, but they are rare and expensive. For holding force, size matters more than grade.
Can you tell a magnet's grade from the outside?
No. An N35 and an N52 look the same. The grade only shows from the specification or a measurement of the remanence.
Is a higher grade also less brittle or more rust-resistant?
No. All grades are equally brittle and need a coating against rust. See why do neodymium magnets rust?
How strong is a neodymium magnet in kilos?
That mainly depends on the size. How strong is a neodymium magnet? has a table with the holding force per size.
Read also
- How strong is a neodymium magnet? Holding force per size
- What is remanence (Br)?
- How is holding force determined?
- All neodymium magnets
Need help choosing? Use the Magnet Advisor or contact us.
