Calculating magnet power and parameters – intensity and induction
Precise calculations for NdFeB magnets
Choosing the right magnet requires analyzing many variables. Magnets differ not only in shape and dimension but primarily in the material grade. Remember the fundamental rule of physics: there are no single-pole magnets. Magnetic monopoles are still a theory – if you manage to discover them, the Nobel Prize in Physics is yours.
Magnetism is an interaction (attraction or repulsion) that depends on specific physical parameters. Every magnet, including a neodymium one, always has two poles: north (N) and south (S). Even if you cut it in half, you won't separate the poles – you will simply get two smaller, complete magnets.
Magnetism is an interaction (attraction or repulsion) that depends on specific physical parameters. Every magnet, including a neodymium one, always has two poles: north (N) and south (S). Even if you cut it in half, you won't separate the poles – you will simply get two smaller, complete magnets.
Select a magnet shape below to start calculations:
| magnet grade properties: | |||||
|---|---|---|---|---|---|
| system: | CGS | SI | |||
| grade: | |||||
| remanence: | (Br) | kGauss | Tesla | ||
| coercivity: | (Hcb) | kOe | kA/m | ||
| intrinsic coercivity: | (Hcj) | kOe | kA/m | ||
| energy density: | (BH Max.) | MGOe | kJ/m³ | ||
| max. working temp.: | °C | ||||
Remember that the final pull force (besides just the thickness of the magnet) is also influenced by:
- material grade (e.g. N38 vs N52),
- potential magnetic assemblies (e.g. closing the circuit with steel).
- magnet shape and contact surface area (the larger, the better),
- the magnet's own weight,
In laboratory conditions – yes. In everyday life – rarely. The force given in the parameters is the perpendicular force (breakaway), measured on perfectly smooth, thick steel. In practice, force drops drastically when:
- the steel is thin (car body sheet),
- the surface is rough, dirty, or painted (air gap),
- you pull the magnet at an angle (shear force is much lower than breakaway force).
That's why we always recommend assuming a safety margin and choosing a magnet stronger than a simple weight conversion suggests.
- the steel is thin (car body sheet),
- the surface is rough, dirty, or painted (air gap),
- you pull the magnet at an angle (shear force is much lower than breakaway force).
That's why we always recommend assuming a safety margin and choosing a magnet stronger than a simple weight conversion suggests.
The symbol N stands for neodymium (NdFeB material), and the number next to it (e.g., 35, 42, 52) is the "Maximum Energy Product" (BHmax) expressed in MGOe. In simple terms: the higher the number, the stronger the magnet at the same volume. An N52 magnet is about 60% stronger than an N35 one.
Most standard magnets are grade N38-N45, which offers the best power-to-price ratio. Higher grades (N48+) are used where space is tight but powerful force is needed (e.g., in miniature electronics).
Important: The calculator estimates force for standard, bare magnets. Magnets in steel housings (pot magnets) or those mounted in arrays (e.g., Halbach) will have completely different characteristics.
Most standard magnets are grade N38-N45, which offers the best power-to-price ratio. Higher grades (N48+) are used where space is tight but powerful force is needed (e.g., in miniature electronics).
Important: The calculator estimates force for standard, bare magnets. Magnets in steel housings (pot magnets) or those mounted in arrays (e.g., Halbach) will have completely different characteristics.
Theoretically, breakaway force can be calculated from surface flux density, but 'paper' calculations often miss reality. Our algorithm is based on hundreds of real physical measurements of magnets with various dimensions. Thanks to data interpolation (calculating between known points), we can precisely estimate the force for any size. We rely on experimental data from reputable leaders like K&J Magnetics.