Neodymium Magnet Grades Explained: N35 to N52SH

If you’ve ever looked at a magnet spec and seen something like N42SH or N38EH, it’s not always obvious what these numbers and letters represent, or why one neodymium grade is recommended over another. The grade designation is simply a way of defining two things: how strong the magnet is, and how well it performs at elevated temperatures.

Date

21 April 2026

What does the grade number mean?

The ‘N’ prefix stands for neodymium. The number that follows – 35, 38, 42, 52, and so on – represents the maximum energy product (BHmax) of the magnet material, measured in Mega Gauss Oersteds (MGOe).

BHmax is the single most important measure of a permanent magnet’s strength. It describes the maximum magnetic energy density the material can store and deliver.

It is measured at the optimal point on the magnet’s demagnetisation curve – where the product of magnetic flux density (B) and magnetic field strength (H) is at its highest.

In practical terms, a higher BHmax means you can produce a stronger magnetic field from a smaller volume of material.

Worked example: An N42 magnet has a BHmax of approximately 40–44 MGOe (318–350 kJ/m³). The grade number ’42’ sits in the midpoint of this energy product range. An N52 magnet has a BHmax of approximately 49–53 MGOe (390–422 kJ/m³) — roughly 25% more magnetic energy per unit volume than N42.

Why higher is not always better

N52 is the strongest commercially available standard neodymium grade. But specifying it for every application is neither necessary nor cost-effective – and in some cases it is actively the wrong choice.

Cost: Higher grades cost more. The price difference between N35 and N52 is significant. If N42 meets your pull force requirement in the available space, N52 adds cost with no benefit.

Temperature sensitivity: Standard high-grade materials (N48, N50, N52) have lower intrinsic coercivity than lower grades with temperature suffixes. An N52 will demagnetise permanently at lower operating temperatures than an N38EH. The strongest magnet at room temperature is not the most capable at elevated temperatures.

Size: In some sensor applications, an overpowered magnet produces a field that is too strong for the detection circuit. The right grade is the one that produces the required field at the required distance – not the maximum possible.

Manufacturability: The highest grades (N50–N52) are not available in all shapes, sizes, and coatings. Availability narrows as grade increases.

What does the grade letter mean? Temperature suffixes explained: M, H, SH, UH, EH

The letter or letters after the grade number indicate the magnet’s intrinsic coercivity class – and by extension, the maximum operating temperature it can sustain without permanent magnetic loss.

Technically speaking, the suffix indicates the minimum Hcj (intrinsic coercivity) the material must achieve. Higher Hcj means the material is harder to demagnetise – which is what allows it to operate at higher temperatures without irreversible loss. This is achieved primarily by adding dysprosium (Dy) and/or terbium (Tb) to the NdFeB alloy, both of which are expensive rare earth elements. This is why temperature-rated grades cost more than standard grades of the same BHmax number.

Suffix	Full name	Max operating temp	Min Hcj (kA/m)	BHmax trade-off	Typical use case
(none)	Standard	80°C	≥955	Full BHmax available — highest strength grades possible	Consumer electronics, room-temp industrial, general use
M	Medium	100°C	≥1114	Slight BHmax reduction vs standard at same grade number	Mild industrial, outdoor near-ambient applications
H	High	120°C	≥1353	Moderate BHmax trade-off. H grades widely available N35–N48	Automotive, outdoor, light industrial with heat exposure
SH	Super High	150°C	≥1592	Notable BHmax reduction. Max available grade drops to ~N45	Industrial motors, pumps, moderate-heat applications
UH	Ultra High	180°C	≥1990	Significant trade-off. Grades typically up to N42–N45	High-performance motors, demanding industrial
EH	Extremely High	200°C	≥2388	Strong trade-off. Grades typically up to N38–N40	Downhole tools, high-temp industrial, autoclave-adjacent
AH / VH	Advanced High	220–230°C	≥2786	Max grade typically N35–N38. Specialist, less common	Extreme-environment specialist applications

The critical trade-off: BHmax vs temperature capability

Achieving higher Hcj requires adding dysprosium or terbium to the alloy. These elements increase coercivity but reduce the remanence (Br) and therefore the BHmax. This is why the highest-grade standard materials (N50, N52) are only available without a temperature suffix – pushing to N52 leaves no room in the alloy composition for coercivity-enhancing elements. In practice: if you need both high strength and high-temperature performance, you are working with a smaller selection of grades. An N42SH offers a better balance than trying to squeeze N52 into a hot environment where it will demagnetise.

The Dysprosium Supply Consideration & Rare Earth Export License Requirements

Dysprosium (Dy) is one of the scarcest and most supply-constrained rare earth elements, with global production heavily concentrated in China. In NdFeB magnets, Dy is added to increase intrinsic coercivity (Hcj), allowing the material to maintain magnetic performance at elevated temperatures.

Temperature-rated grades (e.g. H, SH, UH, EH) contain progressively higher levels of Dy. High-temperature grades such as EH can contain up to ~8–10% Dy by weight, although exact content varies by manufacturer and grade specification. This addition significantly increases raw material cost and introduces supply chain exposure.

In recent years, China has implemented tighter controls on the export of certain rare earth materials and magnet products, with some higher-coercivity or Dy-containing grades requiring export licences. Approval timelines can extend lead times by several weeks, particularly during periods of high demand or regulatory scrutiny. The table below outlines which commonly specified grades are currently subject to export licence requirements.

Where operating temperatures are close to the limit, it is often worth assessing whether a design adjustment – such as increasing magnet volume, improving thermal management, or altering the magnetic circuit—could allow the use of a lower coercivity grade. This can reduce both cost and dependency on constrained materials.

GUK Magnetics supports customers at the specification stage by advising on these trade-offs, helping balance performance, cost, and supply risk. Read our full breakdown of China’s export license restrictions and how they are impacting rare earth magnet supply.

How to choose the right grade: a practical decision framework

Grade selection is not about finding the strongest possible magnet – it is about finding the grade that reliably meets your application requirements in service, at the lowest cost and risk. Work through these questions in order.

Step 1: What is the maximum operating temperature?

This is the single most important question. Not the ambient temperature – the temperature the magnet itself will reach in service, accounting for heat generated by surrounding components (motor windings, electronics, proximity to heat sources).

Below 80°C continuously: Standard grade (no suffix). Full range of BHmax available.
80–100°C: M suffix minimum. Consider H for safety margin if temperature is uncertain.
100–120°C: H suffix minimum.
120–150°C: SH suffix minimum.
150–180°C: UH suffix minimum.
180–200°C: EH suffix minimum.
Above 200°C continuously: Consider samarium cobalt (SmCo). NdFeB approaches its practical limit at EH grades. SmCo operates reliably to 300–350°C.

Always derate for safety

The maximum operating temperatures quoted are limits, not design targets. The closer your magnet operates to its Hcj-limited threshold, the greater the risk of irreversible loss if temperature spikes. As a rule, design to a continuous operating temperature at least 20°C below the grade’s stated maximum. If the application involves thermal cycling, apply additional margin.

Step 2: Is space constrained?

If the magnet must fit within a defined envelope and produce a specific pull force or field strength, a higher-BHmax grade allows you to use a physically smaller magnet. This can justify the cost premium of a higher grade where space is genuinely limiting — for example, in compact motor designs, miniaturised sensors, or wearable devices.

If space is not limiting, a larger lower-grade magnet will typically be more cost-effective. You can use our magnetic force calculator to model the effect of size vs grade changes on pull force to help judge what grade is needed.

Step 3: What is the environment?

Standard NdFeB magnets are susceptible to corrosion – the iron content oxidises readily in humid, wet, or salt-laden environments. Grade selection should be made alongside coating selection. A higher-grade magnet with the wrong coating in a corrosive environment will fail faster than a lower-grade magnet with the right protection.

Dry indoor environments: Standard NiCuNi (nickel) coating. Any grade appropriate.
Humid or outdoor environments: Epoxy or zinc coating. Grade selection unchanged but coating is critical.
Salt spray, marine adjacent, chemical exposure: Epoxy or PTFE coating. Consider whether SmCo is more appropriate for genuinely harsh environments – its inherently better corrosion resistance (especially SmCo5) may be the better engineering decision.
Food-contact, medical, or cleanroom: PTFE, gold, or parylene coating. Grade selection secondary to coating and biocompatibility requirements.

Step 4: What is the budget sensitivity?

Grade has a direct impact on cost. The approximate price differential between adjacent standard grades is 3–8% per step. The cost premium for temperature suffixes is more significant — an N42SH is typically 15–25% more expensive than N42 standard, reflecting the dysprosium content. An N38EH may cost 40–60% more than N38 standard.

For high-volume production programmes, even small grade optimisations compound significantly. Our engineers regularly review specifications at quotation stage and will flag where a lower-cost grade would meet the stated performance requirement.

Step 5: Are there special requirements?

Some applications have requirements beyond the standard grade/suffix framework:

Dy/Tb-free grades: Specified for supply chain resilience or cost reasons. Achieves H or SH performance through alloy optimisation rather than dysprosium addition. Limited availability – discuss with GUK at enquiry stage.
REACH and RoHS compliance: All standard grades comply. Confirm on COC (Certificate of Conformance) if required by your customer or application standard.
Radiation environments: Neodymium magnets are affected by ionising radiation. Nuclear and space applications require specialist discussion — standard grade designations do not address radiation tolerance.
Very tight field tolerances: Where the magnetic field at a specific point must be within a narrow band, grade selection interacts with geometry, magnetisation uniformity, and inspection requirements. Discuss with GUK’s technical team.

Custom Magnet Manufacturing - GUK Magnetics

Working with GUK Magnetics

GUK supplies a wide range of neodymium (NdFeB) magnet grades. If you are unsure which grade is best suited to your application, our team can advise on selection, ensuring the chosen material performs reliably in its intended use.

What to provide when requesting a quote

To receive an accurate recommendation and quotation, the most useful information to provide is:

Shape and dimensions – a 2D drawing (PDF, DXF) or 3D model (.STEP) is preferred. Approximate dimensions are sufficient for an initial discussion.
Material requirement or performance target – either a specific grade (e.g. N42SH) or a performance requirement (e.g. minimum pull force of 25N on a 3mm steel plate, operating to 130°C).
Magnetisation direction – axial, diametric, through-thickness, radial (for rings), or custom if known.
Coating requirement – if known. If not specified, GUK will recommend based on application context.
Quantity – both the initial order quantity and the expected annual volume.

Need help choosing the right neodymium grade?

Speak to our team about magnetic strength, operating temperature, coatings and the most suitable NdFeB grade for your application.

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Frequently asked questions

In the same size and shape, yes — a higher BHmax grade will produce more pull force. However, pull force also depends heavily on magnet geometry, air gap, and the material it is attracting. A larger N38 magnet will often outperform a smaller N52 magnet of equivalent cost. The practical answer is to define your required pull force and available space first, then use the grade as a lever to meet that requirement in the given envelope. GUK’s magnetic force calculator can help model these trade-offs before finalising a specification.

The default coating for neodymium magnets is NiCuNi — a three-layer nickel-copper-nickel plating that provides good corrosion resistance for indoor applications. It is the most widely specified coating and is applied unless an alternative is requested. If your application involves humidity, outdoor exposure, chemical contact, or food-safe requirements, you should specify an alternative coating — epoxy, PTFE, zinc, or gold depending on the environment. Coating selection does not affect grade selection but should be considered alongside it. See GUK’s coating guide for detailed selection guidance.

N55 is the strongest commercially available standard neodymium grade, with a BHmax of approximately 51–55 MGOe. It is important to note that N55 is only the strongest at lower temperatures – in applications involving heat above 80°C, a temperature-rated grade such as N42SH or N38EH will retain far more performance in service than N52, which will begin to demagnetise permanently if its operating temperature is exceeded.

SH stands for ‘Super High’ coercivity. It indicates that the magnet’s alloy has been formulated to achieve a minimum intrinsic coercivity (Hcj) of approximately 1,592 kA/m, which allows it to operate continuously up to 150°C without permanent magnetic loss. The SH suffix is achieved by adding dysprosium to the NdFeB alloy, which increases coercivity at the cost of some reduction in BHmax compared to the standard version of the same grade. N42SH is one of the most commonly specified industrial grades for motor and actuator applications.

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Neodymium Magnet Grades Explained: N35 to N52SH