Neodymium Magnet Grades Chart: N35–N55
Every sintered NdFeB grade in one reference: what the number and letters mean, the magnetic properties behind each grade, which grade/temperature-class combinations actually exist, and how to pick the right one instead of defaulting to N52.
How to read a grade
A sintered NdFeB grade like N42SH encodes three things:
Sintered neodymium iron boron. (SmCo, ferrite, and alnico use different systems — see the material comparison.)
Nominal maximum energy product (BH)max in MGOe — the headline "strength" number. Higher = more flux from the same volume.
Intrinsic coercivity tier — resistance to demagnetization at temperature. No suffix = 80 °C class; AH = 230 °C class.
The two axes are independent: the number tells you how strong the magnet is, the letters tell you how hot it can run. They trade against each other in manufacturing (and in price — the letters cost more than the number, because higher classes use heavy rare earths; see Magnet Pricing Explained).
The grades chart (N35–N55)
Typical property ranges for standard-class (no suffix) sintered NdFeB grades. Values are industry-typical nominal ranges; the governing numbers for any purchase are the minimums on your supplier's datasheet.
| Grade | Br (kG) | Br (mT) | Hcb (kOe) | Hcj (kOe) | BHmax (MGOe) | Max op. temp* |
|---|---|---|---|---|---|---|
| N35 | 11.7–12.1 | 1170–1210 | ≥10.9 | ≥12 | 33–36 | 80 °C |
| N38 | 12.2–12.5 | 1220–1250 | ≥11.3 | ≥12 | 36–39 | 80 °C |
| N40 | 12.5–12.8 | 1250–1280 | ≥11.4 | ≥12 | 38–41 | 80 °C |
| N42 | 12.8–13.2 | 1280–1320 | ≥11.5 | ≥12 | 40–43 | 80 °C |
| N45 | 13.2–13.8 | 1320–1380 | ≥11.6 | ≥12 | 43–46 | 80 °C |
| N48 | 13.8–14.2 | 1380–1420 | ≥11.6 | ≥12 | 45–49 | 80 °C |
| N50 | 14.0–14.5 | 1400–1450 | ≥11.6 | ≥12 | 47–51 | 80 °C |
| N52 | 14.3–14.8 | 1430–1480 | ≥11.6 | ≥12 | 49–52 | 80 °C |
| N55 | 14.6–15.0 | 1460–1500 | ≥11.6 | ≥12 | 52–55 | 80 °C |
*80 °C assumes a favorable permeance coefficient; thin open-circuit magnets have lower real limits. Higher temperature classes of each grade raise Hcj (next section) while Br falls slightly per class step.
Between N35 and N52 the energy product rises ~50%, but Br — which drives field and pull force — rises only ~20%. Stepping up one grade (N42→N45) typically buys ~3–4% more field. Grade steps are refinements, not multipliers: if a design misses its flux target by 30%, the fix is geometry or circuit design, not a grade bump.
Temperature classes (N → AH)
The letter suffix sets the minimum intrinsic coercivity (Hcj) — the property that determines how much heat and opposing field the magnet survives without permanent loss:
| Class | Min Hcj (kOe) | Max op. temp* | Typical duty |
|---|---|---|---|
| (none) | ≥12 | 80 °C | Ambient consumer & industrial |
| M | ≥14 | 100 °C | Warm enclosures, general industrial |
| H | ≥17 | 120 °C | Motors, sensors near heat |
| SH | ≥20 | 150 °C | Automotive underhood, pumps |
| UH | ≥25 | 180 °C | EV traction motors, downhole |
| EH | ≥30 | 200 °C | Aerospace, high-temp actuators |
| AH | ≥35 | 230 °C | Extreme environments |
*Same permeance-coefficient caveat as above — the rating is a material capability, not a guarantee for every geometry.
Each class step is achieved by substituting heavy rare earths (dysprosium/terbium) into the alloy, which slightly reduces Br. That's why an N42SH is a touch weaker at room temperature than a plain N42 — but far stronger at 120 °C, where the plain grade is already losing flux permanently.
Which combinations exist
Not every number pairs with every letter — high energy product and high coercivity fight each other metallurgically. Commercial availability, approximately:
| Grade | — | M | H | SH | UH | EH | AH |
|---|---|---|---|---|---|---|---|
| N35 | ● | ● | ● | ● | ● | ● | ● |
| N38 | ● | ● | ● | ● | ● | ● | limited |
| N40 | ● | ● | ● | ● | ● | limited | — |
| N42 | ● | ● | ● | ● | limited | — | — |
| N45 | ● | ● | ● | ● | limited | — | — |
| N48 | ● | ● | ● | limited | — | — | — |
| N50 | ● | ● | limited | — | — | — | — |
| N52 | ● | limited | — | — | — | — | — |
| N55 | ● | — | — | — | — | — | — |
"Limited" = produced by some mills, longer lead times and premiums; availability shifts as grain-boundary-diffusion processing improves. Confirm current availability at quote.
A hot application can't just "spec N52SH" — it doesn't meaningfully exist. Above ~120 °C the strongest realistic options step down the ladder (N45SH, N42UH, N38EH, N35AH), which is why high-temperature machines are designed around N38–N45 grades, and why the highest N-numbers only appear in room-temperature products.
How to choose a grade
- Start from temperature, not strength. Establish max continuous temperature (plus excursions), pick the letter class first, then take the highest N-number available in that class that the budget supports.
- N42 is the workhorse for a reason — near the top of the strength-per-dollar curve, universally stocked, available in every useful temperature class. Make it your default and deviate with a reason.
- Buy N50–N55 for genuine space constraints only. The last few MGOe carry premium pricing, tighter supply, and the lowest coercivity headroom on the chart.
- Check the load line, not just the class. A thin disc in open circuit can suffer loss below its class rating; a well-designed circuit can exceed it. Give your supplier the geometry and the working environment — see the RFQ guide.
- Or specify the requirement instead of the grade — flux at the working point, temperature, demagnetizing exposure — and let the supplier propose the cheapest grade that meets it.
For an interactive walk-through, the configurator and the grade selector in our engineering resource hub apply this logic to your inputs.
Naming systems & datasheet fine print
- The N-system is effectively universal. It originates from the Chinese GB/T standard grades and is used worldwide; IEC-style codes (e.g., "REN42"-type designations) and legacy manufacturer names map onto the same property tiers. When comparing suppliers, compare the property tables, not the letters.
- Grades are minimum-based ranges. "N42" guarantees BHmax and Hcj minimums; typical production sits mid-range. Two certified N42 lots can differ a few percent in Br — relevant when you tune a sensor to a golden sample.
- Bonded NdFeB uses different scales. Compression-bonded material runs roughly BHmax 8–12 MGOe — the N-chart above applies to sintered material only. See sintered vs. bonded.
- Beware "up to" marketing. A listing that says "N52 performance" without a property table or certification isn't specifying anything. The chart's numbers are only meaningful alongside a per-lot certificate.
Verifying the grade you paid for
Grade verification is a solved problem — insist on the paperwork:
- Per-lot material certificate reporting measured Br, Hcb, Hcj, and BHmax from hysteresisgraph testing against the grade minimums.
- Part-level acceptance via helmholtz-coil total moment limits, which catches under-saturation and undersize that a material cert can't.
- A surface gaussmeter reading is not a grade check — surface field depends on geometry and probe position far more than on grade.
The full measurement toolkit — and how to write acceptance criteria that hold up — is covered in How Magnets Are Tested & Measured. Every Radial Magnets production lot ships with the material certification described above.