There are times when saying that 1 oersted is like 1 gauss works out well. In some ways, you might argue that these things are really the same. The second half of our Magnet Grades article has a great step-by-step description about how these curves are measured. You can find BH curves for various magnet grades on our BH curves page. One axis of this curve is B (flux density expressed in gauss, comes from the magnet itself) and the other axis is H (the applied or external magnetic field in the magnetizing fixture, expressed in Oe).

It describes how much field strength is required to magnetize a magnet, and more importantly for magnet users, how the magnet will perform. The demagnetization curve of a magnet material describes it magnetic properties. Historically and commonly, this field strength is expressed in A/m or Oe. The magnet is exposed to a magnetic field strong enough to magnetize the magnet. For a brief instant, a strong magnetic field is created by running a lot of electric current through the coil of wire. In practice, this means the magnet material is placed in a fixture, sitting inside a big coil of wire. When manufacturing permanent magnets, magnet material is magnetized by exposing it to an external magnetic field. Stick a magnetometer on the surface of this magnet and we'll measure magnetic flux (often called field strength). For example, a D82 disc magnet has a surface field of about 2,952 gauss. When we think about the 'field strength' at the surface of a magnet (the Surface Field), we're looking for something expressed in gauss. How is this different than the flux density expressed in gauss or tesla? Why are there 2 different units? Are they the same thing? It is commonly expressed in amperes/meter (A/m) or oersted (Oe). There's another, somehow different unit for field strength. The magnetic field diagrams here at use color to indicate the strength of the flux density.The average flux density here on the surface of the earth is about 0.5 gauss, though it varies from 0.22 to 0.6 gauss.We measure field strength with a magnetometer, expressed in gauss.We use flux density to describe the 'field strength' at some distance from a magnet, used in our Pull Force Calculator and in the formulas given in our Surface Fields article.We use flux density to express Surface Field.Technically, we should probably use the term, 'magnetic flux density,' though it's much more commonly called, 'field strength.' Here's a confusing part: Many people call this, 'field strength.' We often refer to field strength in gauss. The conversion between gauss and tesla is an easy one: 1 tesla = 10,000 gauss. By definition, 1 weber per square meter (Wb/m 2) = 1 tesla (T). In fact, webers per square meter is the unit for flux density. Flux Density is a measure how many webers are squeezed into some area. Unlike Magnetic Flux above, the Flux Density defines some size for the loop of wire in that example. In the equations from our Surface Fields article, we use a 'B' to denote this term. This property is also referred to as the B field. The SI unit for flux density, or induction, is the tesla (T).

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