When current flows through a Hall sensor that is positioned in a magnetic field such that the field is vertically oriented to the current direction, the sensor generates an output voltage that is proportional to the product of the magnetic field strength and current. Thus, if the current is known, the strength of the magnetic field can be measured. Also, if the magnetic field is generated by the flow of current through a conductor or coil, the potential-free measurement of the current flowing through the conductor or coil is possible.

A Hall sensor generates a signal even when the magnetic field is constant. This is a key advantage over pairing a magnet and coil, since, with the latter technique, no voltage is induced in the coil when the magnet stands still and thus the magnet cannot be detected.

Applications for Hall sensors:
- Magnetic field measurement (magnetic flux sensing)
- Potential-free current measurement (current sensing)
- Touchless and contactless sensing/signaling
- Coat/layer thickness measurement
- Hall sensors have many uses in the automotive industry: e.g., in seat buckle and door latching systems, pedal position sensing, gear shift systems and for ignition detection. One of their key advantages is their ruggedness against dirt (non-magnetic) and water.
- In power plant engineering, Hall sensors are used to measure turbine speed.