What is a quality grade?
You will often see magnets described with a combination of letters and numbers, such as N42, N42SH or N35UH. On this page, you can see data for these grades and an explanation of how the data should be read.
The short explanation
The numbers tell you how much energy the magnet can deliver — regardless of the magnet's size. The higher the number, the more energy (Maximum Energy Product, MGOe) the magnet can produce. You will therefore experience a higher number as a stronger magnet. A magnet with a grade of 40 is therefore less powerful than a magnet of the same size with a grade of 52.
Before and after the numbers, there is often a letter. The letter on the left tells you the magnet type — this will typically be N for neodymium. The letters on the right tell you about the maximum operating temperature and the Curie temperature. Examples include N42, N42SH, N35UH and others. Often, the letter on the right is omitted, so it simply says N42. In that case, the maximum operating temperature is 80 degrees and the Curie temperature is 310 degrees.
Physical data for the individual quality grades
Below, you can look up the typical physical values for each quality grade. The number indicates the strength, and the letters indicate heat resistance: an N52 is very strong, but only suitable for cooler conditions, while an N35AH is slightly weaker but can handle high temperatures.
| Grade | Remanence Br (T) | Coercivity HcB (kA/m) | Intrinsic coercivity HcJ (kA/m) | Max. energy product (kJ/m³ · MGOe) | Max. operating temperature (°C) | Curie temp. (°C, approx.) |
|---|---|---|---|---|---|---|
| N series – standard, up to ~80 °C | ||||||
| N35 | 1.17–1.21 | 860–915 | ≥955 | 263–279 (33–35) | ≤80 | ~310 |
| N38 | 1.22–1.26 | 860–915 | ≥955 | 287–303 (36–38) | ≤80 | ~310 |
| N40 | 1.26–1.29 | 860–955 | ≥955 | 303–318 (38–40) | ≤80 | ~310 |
| N42 | 1.29–1.32 | 860–955 | ≥955 | 318–334 (40–42) | ≤80 | ~310 |
| N45 | 1.32–1.37 | 860–995 | ≥955 | 342–358 (43–45) | ≤80 | ~310 |
| N48 | 1.37–1.42 | 860–995 | ≥955 | 358–382 (45–48) | ≤80 | ~310 |
| N50 | 1.40–1.46 | 860–995 | ≥955 | 374–406 (47–51) | ≤80 | ~310 |
| N52 | 1.42–1.47 | 860–995 | ≥955 | 380–422 (48–53) | ≤65 | ~310 |
| M series – up to ~100 °C | ||||||
| N35M | 1.17–1.21 | 860–915 | ≥1114 | 263–279 (33–35) | ≤100 | ~320 |
| N42M | 1.29–1.32 | 860–995 | ≥1114 | 318–334 (40–42) | ≤100 | ~320 |
| N45M | 1.32–1.37 | 860–1035 | ≥1114 | 342–358 (43–45) | ≤100 | ~320 |
| N50M | 1.40–1.46 | 860–995 | ≥1114 | 374–406 (47–51) | ≤100 | ~320 |
| H series – up to ~120 °C | ||||||
| N35H | 1.17–1.21 | 860–915 | ≥1353 | 263–279 (33–35) | ≤120 | ~320 |
| N42H | 1.29–1.32 | 860–955 | ≥1353 | 318–334 (40–42) | ≤120 | ~320 |
| N48H | 1.37–1.42 | 860–995 | ≥1353 | 358–382 (45–48) | ≤120 | ~320 |
| SH series – up to ~150 °C | ||||||
| N35SH | 1.17–1.21 | 860–915 | ≥1592 | 263–279 (33–35) | ≤150 | ~340 |
| N42SH | 1.29–1.32 | 860–955 | ≥1592 | 318–334 (40–42) | ≤150 | ~340 |
| N45SH | 1.32–1.37 | 860–955 | ≥1592 | 342–358 (43–45) | ≤150 | ~340 |
| UH series – up to ~180 °C | ||||||
| N30UH | 1.08–1.12 | 804–844 | ≥1990 | 223–239 (28–30) | ≤180 | ~350 |
| N35UH | 1.17–1.21 | 860–915 | ≥1990 | 263–279 (33–35) | ≤180 | ~350 |
| N40UH | 1.26–1.29 | 860–955 | ≥1990 | 303–318 (38–40) | ≤180 | ~350 |
| EH series – up to ~200 °C | ||||||
| N30EH | 1.08–1.12 | 804–844 | ≥2388 | 223–239 (28–30) | ≤200 | ~350 |
| N35EH | 1.17–1.21 | 860–915 | ≥2388 | 263–279 (33–35) | ≤200 | ~350 |
| N38EH | 1.22–1.25 | ≥899 | ≥2388 | 287–310 (36–39) | ≤200 | ~350 |
| AH series – up to ~230 °C | ||||||
| N30AH | 1.08–1.13 | ≥819 | ≥2624 | 223–247 (28–31) | ≤230 | ~350 |
| N35AH | 1.17–1.22 | ≥876 | ≥2624 | 263–287 (33–36) | ≤230 | ~350 |
| N38AH | 1.22–1.25 | ≥899 | ≥2624 | 287–310 (36–39) | ≤230 | ~350 |
Explanation of the terms
What does the grade of a magnet mean?
The grade is the code shown on the magnet, for example N42, N52 or N42SH. In short, the code tells you two things:
- How strong the magnet is
- How much heat it can withstand
The letter N means that it is a neodymium magnet.
The number, for example 42 or 52, says something about the magnet's strength. The higher the number, the more magnetic energy is packed into the material. An N52 is therefore stronger than an N42, provided the magnets have the same size and shape.
The letters?
The letters after the number tell you how heat-resistant the magnet is.
If there is no letter after the number, it is a standard neodymium magnet
that can typically be used up to around 80 °C.
Designations such as M, H,
SH, UH, EH and
AH mean that the magnet can withstand higher temperatures.
It is important to understand that the letters after the number do not make
the magnet stronger. They only refer to heat resistance. An N42
and an N42SH are therefore approximately equally strong, but
N42SH can withstand more heat.
Remanence, Br — the magnet's own strength
Remanence describes how strong a magnetic field the magnet
itself creates.
In practice, you can think of it as a measure of how strongly the magnet can
pull. The higher the remanence, the stronger the magnetic field and normally
also the stronger the pull.
Remanence is measured in Tesla (T). You may also come across the older unit Gauss. 1 Tesla equals 10,000 Gauss.
Coercivity, HcB — how difficult the magnet is to weaken
Coercivity describes how well the magnet resists being
weakened by a magnetic field acting in the opposite direction.
This can happen, for example, if the magnet is placed close to other powerful
magnets that pull in another direction. The higher the coercivity, the more
force is required before the magnet's strength is pushed down.
For everyday use, this is rarely something you need to worry about. But in motors, generators and technical magnetic systems, it can be important because the magnets are often placed close together and affect each other.
Intrinsic coercivity, HcJ — the magnet's resistance to permanent damage
Intrinsic coercivity describes how difficult it is to
permanently destroy the magnet's magnetism.
You can think of it as the magnet's internal safety margin. The higher the
intrinsic coercivity, the better the magnet can withstand conditions that
would otherwise cause it to lose strength permanently.
This is especially important with heat. When a magnet becomes hot, it becomes
easier to weaken it permanently. This is why heat-resistant magnets such as
H, SH, UH,
EH and AH typically have a higher intrinsic
coercivity than standard neodymium magnets.
In short: intrinsic coercivity is one of the main reasons why some magnets can withstand higher temperatures than others.
Maximum energy product, BHmax — how much magnetism is packed into the material
BHmax describes how much magnetic energy the material can
hold relative to its size.
It is an overall measure of the magnet's performance. The higher the BHmax,
the more magnetic force you get from the same amount of material.
This is actually the number the grade is based on. An N42,
for example, has a maximum energy product of around 42 MGOe.
BHmax can be stated in kJ/m³, which is the SI unit, or in MGOe, which is an older but still widely used unit in the magnet industry.
Maximum operating temperature — the temperature you should plan for
The maximum operating temperature is the highest temperature
at which the magnet should be used in practice.
If the magnet becomes hotter than this limit, it may lose some of its strength
permanently. This means it will not necessarily become strong again, even
after it cools down.
The limit depends not only on the magnet type but also on the magnet's shape.
A thin, flat magnet is typically more sensitive to heat than a thicker and
more compact magnet of the same grade.
Therefore, the maximum operating temperature is the most important temperature limit to use when choosing a magnet.
Curie temperature — the absolute limit
The Curie temperature is the temperature at which the magnet
material loses its magnetism completely.
This may sound like the most important temperature, but in practice it is less
relevant in normal use. The magnet begins to lose strength long before it
reaches its Curie temperature.
The Curie temperature is therefore mostly a theoretical outer limit. When you need to choose a magnet for a specific application, you should look at the maximum operating temperature — not the Curie temperature.
What should I know about quality grade before buying a magnet?
Whether you need magnets for an electric motor or for lifting an object, it is important to know the magnet's strength. If the magnet is too powerful (the grade is too high), it can damage its surroundings. If the magnet is too weak (the grade is too low), you may not get the desired result. In addition to the grade, there are also other factors that affect a magnet's strength. These include, for example:
- The magnet's shape and proportions
- The magnet's volume
- The magnet's surroundings — for example, if the magnet is covered by metal, or if the metal the magnet needs to stick to is not 100 % magnetic.
As shown above, quality grade is a theoretical value that can be difficult to relate to or convert into practical use. That is why we also measure the strength of our magnets by testing how many kg they can hold. You can find this information on the individual product pages.