The oersted (abbreviated as Oe) is the unit of magnetic-field strength |H| in the cgs (centimetre-gram-second) system of physical units.
The unit is named after Hans Christian Oersted. It is defined as the strength of a magnetic field in vacuum: A unit magnetic pole in a field of one Oe experiences a mechanical force of one dyne ( = 10−5 newton) in the direction of the field. Note here that in the cgs system a unit magnetic pole repels a like pole at a distance of one centimetre with a force of one dyne. One oersted equals 1000/4π A/m [ampere per meter, the SI unit for |H| ].
Before 1932 the oersted was known as the gauss, a name sometimes still applied, though now more properly used for the cgs unit of strength of magnetic induction |B|.