How do you measure the strength or power of a magnet?
Most commonly, gaussmeters, magnetometers, or pull testers are used to measure the strength of a magnet. Gaussmeters measure strength in gauss; magnetometers measure in gauss or arbitrary units (making it easy to compare one magnet to another); pull testers measure pull in pounds, kilograms, or other units of force. Helmholtz coils, search coils, and permeameters are also used for sophisticated measurements of magnets.
Special gaussmeters can cost up to several thousand euros.