'''Magnetic flux''', represented by the Greek letter Φ ([[Phi (letter)|phi]]), is a measure of quantity of [[magnetism]], taking into account the strength and the extent of a [[magnetic field]]. The [[SI]] [[unit of measurement|unit]] of magnetic flux is the [[Weber (unit)|weber]] (in derived units: volt-seconds), and the unit of magnetic field is the weber per square meter, or [[Tesla (unit)|tesla]].
Image:Surface integral illustration.png|right|thumb|Figure 1: The definition of surface integral relies on splitting the surface into small surface elements. Each element is associated with a vector d'''S''' of magnitude equal to the area of the element and with direction normal to the element and pointing outward.]]
[[Image:Surface normal.png|right|thumb|300px|Figure 2: A vector field of normals to a surface.]]
The [[flux]] through an element of [[area]] [[perpendicular]] to the direction of magnetic field is given by the product of the [[magnetic field]] and the [[area]] element.