If I have a neo magnet with a Br of 12,300 gauss, can I measure 12,300 gauss on its surface?
No. The Br value is measured in a closed circuit. A closed magnet is not very useful. In practice, you will measure a field of less than 12,300 gauss near the surface of the magnet. The actual measurement depends on whether the magnet is attached to steel, how far from the surface you take the measurement, and the size of the magnet (assuming the measurement is taken at room temperature). A neodymium magnet 1" in diameter and ¼" long measures about 2,500 gauss at 1/16" from the surface and 2,200 gauss at 1/8" from the surface.
