Most commonly, Gaussmeters, Magnetometers, or Pull-Testers are used to measure the strength of a magnet. Gaussmeters measure the strength in Gauss, Magnetometers measure in Gauss or arbitrary units (so its easy to compare one magnet to another), and Pull-Testers can measure pull in pounds, kilograms, or other force units. Special Gaussmeters can cost several thousands of dollars. 

There are 2 types of magnets: permanent magnets and electro-magnets.Permanent magnets emit a magnetic field without the need for any external source of power. Electro-magnets require electricity in order to behave as a magnet.There are various different types of permanent magnet materials, each with their own unique characteristics. Each different material has a family of grades that have properties slightly different from each other, though based on the same composition.

Most modern magnet materials have a "grain" in that they can be magnetized for maximum effect only through one direction. This is the "orientation direction", also known as the "easy axis", or "axis".Unoriented magnets (also known as "Isotropic magnets") are much weaker than oriented magnets, and can be magnetized in any direction. Oriented magnets (also known as "Anisotropic magnets") are not the same in every direction - they have ...

The amount of magnetism [brmax at the center] of a magnet is measured in Gauss. This is a measure of the penetration of a magnet. Below is a table of the Gauss ratings of the most popular neodymium magnets:Grade GaussN35 11,700-12,100N38 12,100-12,500N40 12,600-12,900N42 12,900-13,200N45 13,500-13,800N48 14,000-14,200N50 14,300-14,500N52 14,600-14,800

The strength of neodymium magnets is given by a grading from N24 for the lowest strength magnets to N52 for the strongest we carry.Each number higher is about 1% stronger than the previous number grade.