# What is the definition of magnetic flux?

Magnetic flux is defined as the number of magnetic field lines passing through a given closed surface. It provides the measurement of the total magnetic field that passes through a given surface area. Here, the area under consideration can be of any size and under any orientation with respect to the direction of the magnetic field.

Symbol of magnetic flux

• Magnetic flux is commonly denoted using the Greek letter Phi or Phi suffix B.
• Magnetic flux symbol: Φ or ΦB.

### Calculation of magnetic flux

The magnetic flux formula is given by,

$$\Phi _{B}= B.A$$ $$\Phi _{B}= B.A \cos \Theta$$

Where,

B = Magnetic field,

A =  Surface area and

Θ =  Angle between the magnetic field and normal to the surface.