Contact Us Now
Name can't be empty
Email error!
Message can't be empty
Send Message
Estimate the axial magnetic flux density at the center of a magnet pole face. This calculator is intended for quick engineering evaluation of disc/cylinder magnets and rectangular block magnets before sample measurement.
The calculator assumes an axially magnetized magnet with uniform magnetization. The result is the axial field on the centerline of the pole face, with optional measurement gap from the surface.
| Shape | Input | Ideal Formula Used | Engineering Notes |
|---|---|---|---|
| Disc / Cylinder | Diameter D, thickness T, gap g, Br | B = Br / 2 x ((T + g) / sqrt(R^2 + (T + g)^2) - g / sqrt(R^2 + g^2)) | R = D / 2. At g = 0, this gives the ideal center surface field. |
| Block / Rectangular | Length L, width W, thickness T, gap g, Br | B = Br / (4 x pi) x (Omega(g) - Omega(g + T)) | Omega(z) is the solid angle of the rectangular pole face at distance z. |
Surface field is easy to measure but sensitive to many details. Use this calculator for comparison and early estimation, then confirm final values with actual samples and a calibrated gaussmeter.
Values below are approximate reference values for quick calculation only. Always use the material datasheet value when available.
| Material | Grade | Approx. Br (T) | Approx. Br (G) | Common Use |
|---|---|---|---|---|
| NdFeB | N35 | 1.17 | 11700 | General-purpose high-strength magnets |
| NdFeB | N38 | 1.21 | 12100 | Balanced performance and cost |
| NdFeB | N40 | 1.25 | 12500 | Common industrial magnets |
| NdFeB | N42 | 1.29 | 12900 | Higher strength standard grade |
| NdFeB | N45 | 1.33 | 13300 | High-performance general use |
| NdFeB | N48 | 1.38 | 13800 | Compact high-force designs |
| NdFeB | N50 | 1.42 | 14200 | High Br applications |
| NdFeB | N52 | 1.45 | 14500 | Maximum energy grade selection |
| SmCo | SmCo 1:5 | 0.85 | 8500 | High-temperature and corrosion-resistant applications |
| SmCo | SmCo 1:5 High Br | 0.90 | 9000 | Higher output SmCo 1:5 applications |
| SmCo | SmCo 2:17 | 1.00 | 10000 | High-temperature motor and sensor applications |
| SmCo | SmCo 2:17 High Br | 1.05 | 10500 | High-temperature designs needing stronger output |
| SmCo | SmCo 2:17 Premium | 1.10 | 11000 | Premium SmCo magnetic performance |
| Ferrite | Y25 / C5 | 0.35 | 3500 | Cost-sensitive permanent magnet applications |
| Ferrite | Y30 / C8 | 0.38 | 3800 | Common ceramic/ferrite magnet grade |
| Ferrite | Y35 | 0.40 | 4000 | Higher Br ferrite magnet selection |
| Ferrite | High Br Ferrite | 0.42 | 4200 | Ferrite designs requiring stronger surface field |