Magnetic flux is measurement of the quantity of magnetism, the description of how certain materials relate to magnetic fields. Specifically, it describes the strength and extent of the object's interaction with the field. This measurement categorizes the magnetic phase of the object. Magnetic flux is measured in units known as a weber, with the consideration that each weber per square meter is referred to as a tesla. The representation of this principle in physics is given as the Greek letter phi.

All materials are subject to a level of flux, either to a lesser or greater degree. Ferromagnetic objects produce a persistent magnetic field on their own, while other elements produce almost none or require exposure to an electrical field to become magnetic. Examples of objects with a naturally-occurring significant magnetic field are cobalt, gadolinium, iron, nickel and the alloys thereof. Depending on the level of attraction to the magnetic field, the magnetic flux can exhibit either paramagnetism, attraction, or diamagnetism, repulsion.

In order for the flux to be measured in an element, the direction of the magnetic field itself must by identified perpendicular to the area influenced by the field. The product of the field and the area is defined as the flux. Essentially, one needs to identify two separate dots within an area, known as the scalar product. By finding the direction of the magnetic field within the area, in terms of north or south polarization, one can determine the level of magnetism. This measurement is proportional to the level of the magnetic field as it passes through the surface of the element.

Two distinct laws exist for the existence of flux and magnetism in general: Gauss's law and Faraday's law. The two divergent principles respond to the concept of what type of surface is relating to the magnetism. As one of Maxwell's equations, Gauss's law for magnetism states that magnetic flux through a surface without boundaries, a closed surface, must be equal to zero. Faraday's law, states that magnetic flux through a surface with boundaries, an open surface, will have a certain quantity of magnetic flux.

Due to Faraday's law, the difference of the positive and negative charges across an open surface generates an electric field. This process is known as electromotive force, which drives current flow in a circuit. In order to measure the magnetic flux in this process, a fluxmeter is used. This device basically measures the change of voltage in the coils of a device influenced by the magnetic flux.