Magnet Tools
Practical tools we use every day when quoting: a weight and volume calculator, a unit converter for the units that magnet datasheets mix together, and a temperature material selector.
Magnet Weight and Volume Calculator
Enter the nominal dimensions and the material to get the weight of one piece and of the whole order.
Densities are typical values and differ slightly between grades and suppliers. Coating weight is not included (it can be noticeable on very small parts). Dimensions are nominal, without tolerances. For exact figures, check the datasheet or weigh a sample.
Important notice: Results are theoretical values calculated from the nominal dimensions and typical densities you enter. Actual weights depend on tolerances, coating and the supplier's material, so they are for general information and preliminary planning only. They are not an offer, a specification or a guarantee, and they do not bind Rami Technics. Please confirm weights and prices against the manufacturer's datasheet or a measured sample before ordering.
Magnet Unit Converter
Convert between the units found on magnet datasheets: SI and CGS magnetic units, force, length, mass and temperature.
Important notice: Conversions are provided for general information and use the standard definitions stated above. Pull-force and other datasheet values are measured under specific test conditions and are not guaranteed values for your application. The results do not bind Rami Technics; please check the original datasheet before taking technical or commercial decisions.
How the weight is calculated
Weight is volume multiplied by density. Volume comes from the nominal dimensions (all converted to millimetres first), then to cm³, and the result is in grams:
| Shape | Volume formula |
|---|---|
| Disc / cylinder | V = π/4 × D² × H |
| Block | V = L × W × H |
| Ring | V = π/4 × (OD² − ID²) × H |
| Arc segment | V = (θ/360) × π/4 × (OD² − ID²) × H |
| Sphere | V = π/6 × D³ |
Mass (g) = volume (cm³) × density (g/cm³). Example: a disc Ø20 × 5 mm in sintered neodymium has a volume of π/4 × 20² × 5 = 1,570.8 mm³ = 1.5708 cm³, so it weighs 1.5708 × 7.5 = 11.78 g. A block 50 × 25 × 10 mm has 12.5 cm³ and weighs 93.75 g.
Densities used (g/cm³)
| Material | Typical density (g/cm³) |
|---|---|
| Sintered neodymium (NdFeB) | 7.5 |
| Samarium cobalt (Sm₂Co₁₇) | 8.4 |
| Samarium cobalt (SmCo₅) | 8.3 |
| AlNiCo (cast) | 7.3 |
| Ferrite (sintered) | 4.9 |
| Flexible (rubber-bonded ferrite) | 3.6 |
These are typical figures, not guarantees. If your supplier gives a density on the datasheet, select “Custom density” and enter it.
About the unit converter
Magnet datasheets mix SI units (tesla, A/m, kJ/m³) and CGS units (gauss, oersted, MGOe). The conversions used are exact definitions: 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.
The number in a neodymium grade name (N35, N42, N52) is roughly the maximum energy product in MGOe, so N42 is about 42 MGOe, or about 334 kJ/m³. Pull force on a datasheet is usually quoted in kg or lb of force (kgf, lbf), measured against a thick, flat steel plate in ideal conditions, so it is not the force you will see in your assembly.