Data Sources and Methods

Magnet grades and temperature values

Grade suffixes, maximum operating temperatures, low-temperature behaviour and material comparisons are taken from manufacturer datasheets and technical publications. The sources are in the reference list below ([1]–[10]). A manufacturer’s maximum temperature does not state a duration and depends on the magnet’s shape and circuit [9], [10].

How the temperature selector decides

The continuous limit is the manufacturer’s maximum minus 20 K; this is our own planning rule for 24/7 duty, not a standard. Very high-energy grades inside a suffix (for example N50, N52, N48M) are rated about 10 K lower [1]. The selector also applies a planning margin that is our own engineering rule of thumb: 10 K for a favourable magnet (thick, or in a closed steel circuit), 20 K for a typical free magnet, 40 K for a thin, flat magnet in open air, and a further 20 K when an opposing field is present. Results are for preliminary planning; the final choice must be verified against the manufacturer’s demagnetisation curves.

Weight calculation

Weight is volume multiplied by density. Volume comes from the nominal dimensions (converted to millimetres first), and the mass is given in grams:

Mass (g) = volume (cm³) × density (g/cm³). Typical densities used:

These are typical figures, not guarantees. Coating weight is not included, and dimensions are nominal, without tolerances.

Unit converter

The conversions are exact by definition: 1 T = 10,000 G; 1 Oe = 1000/4π A/m ≈ 79.577 A/m; 1 MGOe = 100/4π kJ/m³ ≈ 7.9577 kJ/m³; 1 in = 25.4 mm; 1 kgf = 9.80665 N.

Market bulletins

Bulletins are compiled from public news and analysis sources. Each issue lists its sources with author and date in its reference list. These data are not our own measurements.

Calculations run in your browser

The weight calculator, unit converter and temperature selector run in your browser. The dimensions, temperatures or prices you enter are not sent to our server.

References

1. [1]  Eclipse Magnetics Ltd. (n.d.). Sintered Neodymium Iron Boron (NdFeB) Magnets [Technical data sheet]. Sheffield, England. https://www.eclipsemagnetics.com/site/assets/files/2399/neodymium_grades_data.pdf
2. [2]  Arnold Magnetic Technologies. (2015). Temperature effects on magnetic output (TECHNotes TN 0303, rev. 2015a). https://www.arnoldmagnetics.com/wp-content/uploads/2017/10/TN_0303_rev_150715.pdf
3. [3]  Eclipse Magnetics Ltd. (n.d.). Technical data sheet: Samarium cobalt magnets, SmCo magnets. https://www.eclipsemagnetics.com/site/assets/files/19544/eclipsemagnetics_smco_datasheet.pdf
4. [4]  Eclipse Magnetics Ltd. (n.d.). Alnico magnets: Data sheet. https://www.eclipsemagnetics.com/site/assets/files/22210/eclipsemagnetics_alnico_data_sheet.pdf
5. [5]  Goudsmit Magnetics. (2025). Goudsmit ferrite grade system [Grades available at Goudsmit, 22 August 2025]. https://www.goudsmitmagnetics.com/uploads/pdf/ferrite_grades_available_at_goudsmit_20250822_4120.pdf
6. [6]  Arnold Magnetic Technologies. (2025). Plastiform datasheet (US). https://www.arnoldmagnetics.com/wp-content/uploads/2025/05/Plastiform-Datasheet-US-2025.pdf
7. [7]  Trout, S. R., & Constantinides, S. (2015). Using permanent magnets at low temperature (TECHNotes TN 0302, rev. 2015a; original work 2003). Arnold Magnetic Technologies. https://www.arnoldmagnetics.com/wp-content/uploads/2017/10/TN_0302_rev_150715.pdf
8. [8]  Haavisto, M. (2013). Studies on the time-dependent demagnetization of sintered NdFeB permanent magnets (Publication 1180) [Doctoral dissertation]. Tampere University of Technology. https://neorem.fi/wp-content/uploads/2023/01/Studies-on-the-Time-Dependent-Demagnetization-of-Sintered-NdFeB-Permanent-Magnets.pdf
9. [9]  K&J Magnetics, Inc. (n.d.). Temperature and neodymium magnets. https://www.kjmagnetics.com/blog/temperature-and-neodymium-magnets
10. [10]  Liu, J. (2016). Some design considerations using permanent magnets. Magnetics Magazine. https://magneticsmag.com/some-design-considerations-using-permanent-magnets/