What does the term Maximum Energy Product (BHmax) mean?

The maximum energy product of a magnet is expressed in 'Mega-Gauss Oersteds' (MGOe) is measured. Known as the maximum energy product value, this is the primary indicator of the "strength" of a magnet. Generally, the higher the maximum energy product value, the greater the magnetic field the magnet will produce in a given application. In neodymium grading, the two numbers in a grade name (e.g., N42) represent the maximum energy product for that grade. The higher the value, the greater the magnetic field strength the magnet exerts in a given application and the smaller the magnet volume required.
(BH)max is a product of remanence (Br) and coercivity (Hc) and represents the area under the second quadrant hysteresis loop diagram.
Each neodymium magnet has an associated maximum energy product, which is displayed on the Technology Center's "Neodymium Magnet Qualities" page.