It's been many years since I studied this so I would appreciate some confirmation on the formula and its parts. The formula I was taught to calculate the Gauss of an electromagnet was: B=MNI/2R with: B = Magnetic flux in Gauss M= Magnetic permeability of core material N = Number of turns of wire I = Current input in Amps 2R = two times radius (or diameter) of core Question... is this formula correct? I have noticed that the term Tesla is favored over Gauss. As I recall, 1 Tesla equals 10,000 Gauss. Am I correct? I have been quoted by a metal manufacturer that the magnetic permeability of Nickle-Iron is 1,000,000 (one million). That same manufacturer said that NdFeB was 900,000. Do these numbers represent μ? Are these figures proper inputs for the above formula? So lets create a hypothetical electromagnet. We'll use a .25" diameter by 12" long Nickle-iron rod as the core. Using 24 Ga magnet wire (.0201") we can wind a coil 12" long by 7" in diameter. This would equal 220,000 turns of wire. If we then supply it with 500 mA of current it should look like this: B = 1,000,000 x 220,000 x .5 / .25 B= 110,000,000,000 / .25 B = 440,000,000,000 or 440 Billion Gauss Here's my problem: The Mag Lab outside Tallahassee Florida claims to have built the world's strongest electromagnet which is 45 Teslas (450,000 Gauss) in strength. So where have I screwed up in this calculation?