The magnetic force of a magnet, fundamentally generated by the motion of electrons within its material, is its most defining characteristic. This force is quantified by two key parameters: remanence (Br), which indicates the strength of the magnetic field the magnet can produce, and coercivity (Hc), which represents its resistance to being demagnetized. The maximum energy product (BHmax) is a single figure that combines these, describing the overall strength of the magnet. Materials like neodymium iron boron (NdFeB) possess exceptionally high values for these parameters, making them the strongest permanent magnets commercially available, while ferrite magnets offer a lower but cost-effective magnetic force.

The practical strength of the magnetic force experienced in an application depends on several factors beyond the material itself. The grade or N-rating of the magnet (e.g., N52) directly correlates to its maximum energy product. Furthermore, the size and shape are critical; thicker magnets and those with larger surface areas generally produce a stronger pull force. Crucially, the force exerted is not constant and decreases dramatically with increasing distance. It is approximately inversely proportional to the square of the distance from the magnet's surface, meaning doubling the distance can reduce the force to a quarter.

Understanding these principles is vital for selecting the right magnet. For instance, a small, high-grade neodymium magnet might be perfect for a compact sensor, while a larger ferrite magnet could be more suitable for holding a heavy whiteboard. Engineers must balance the required pull force, the available space, and the operating environment, which includes temperature, to ensure the magnet performs as intended throughout its lifespan.