What Is Gauss?
Gauss, also known as the Gauss unit or the gauss, is the magnetic flux density or magnetic induction measurement in a neodymium magnet or a specific location. It is named after the German mathematician Johann Carl Friedrich Gauss, who developed the mathematical formula for measuring magnetic fields.
One unit of gauss is one line of flux in a 1 cm square surface area. It can also be in terms of flux density: 1 G = 1 tesla/meter2 = 10,000 nanoteslas/centimeter2. You cannot compare the gauss or magnetic flux density between two neodymium magnets unless they share the same geometry, i.e., the same size and shape. Also, the readings must be taken from the same location.
Several factors can alter a Gauss reading. Examples include temperature, time, location, nearby electronic devices, and other magnetic fields near the test site. For neodymium magnets that have been stored for future use, routine tests are essential to ensure optimal performance when it is time for their application, as age can affect the neodymium magnets’ strength and field.
Gauss is different from the magnetic pull or magnetizing strength and has a different function. Unlike most people believe, a higher pull power does not necessarily translate to a higher gauss.
For instance, if you have two neodymium magnets with equal pulls at their respective magnetic ends but different gauss levels, the one with the higher gauss will generate a stronger, thicker, and far-reaching magnetic field than the one with the lesser gauss. But both neodymium magnets will pull with the same force, possess the same holding power, and have the same max energy product (BHmax).
Gauss test is usually used to measure the distance or area of the field generated by a neodymium magnet. Still, a neodymium neodymium magnet may not be able to pull certain objects even within its magnetic field because pull strength reduces as the magnetic field thins out.
Hence, the PHMSA (Pipeline and Hazardous Material Safety Administration) rule says for transport by aircraft, any package with a magnetic field of more than 5.25 milligauss (0.00525 gausses) measured at 4.5 m (15 feet) from any surface of the box must be labeled magnetic. And the IATA (International Air Transport Association) rule says if the maximum field strength (gauss) measured at 7 feet is less than two milligauss (0.002 gausses), or there is no significant compass deflection. The package is not restricted to “Magnetized Material” in that case.
These rules imply that a magnetic field is magnetic at 5.25 milligauss since it can deflect a compass. But it is no longer magnetic at below two milligauss since it cannot deflect a compass, even though the magnetic field is present. To test the pull strength of a neodymium magnet, you should perform a strength test using a pull tester. But you will need a gaussmeter or tesla meter to measure the density or strength of the magnetic field.