A dispenser for dispensing a sheet material, comprising: a roll support for supporting a supply of the sheet material; a feed roller arranged along a feed path of the sheet material downstream from the supply of sheet material, the feed roller engaging and pulling the sheet material from the supply of sheet material for feeding along the feed path upon the rotation of the feed roller; a controller in communication with the feed roller and including programming for monitoring rotation of the feed roller during a dispensing cycle for feeding a selected length of the sheet material from the supply of sheet material; a material supply monitoring system in communication with the controller and operable to detect a number of rotations or an angle of rotation of the supply sheet material during at least a series of dispensing cycles, the material supply monitoring system including a plurality of magnets (102, 104) that is rotatable with the supply (26, 27) of sheet material, and at least one sensor operable to measure or detect fluctuations or variations in a magnetic field created as the plurality of magnets (102, 104) is rotated or otherwise moves past the at least one sensor with the rotation of the supply of sheet material, and based upon the fluctuations or variations in the magnetic field, a remaining diameter of the supply of sheet material is substantially dynamically determined after at least each of the series of dispensing cycles; and a drive motor coupled to the feed roller and in communication with the controller, which controls operation of the drive motor to drive the rotation of the feed roller for feeding the selected length of sheet material; wherein the plurality of magnets is arranged to form magnetic ring with adjacent magnets of the plurality of magnets having opposite and alternating polarities. a roll support for supporting a supply of the sheet material; a feed roller arranged along a feed path of the sheet material downstream from the supply of sheet material, the feed roller engaging and pulling the sheet material from the supply of sheet material for feeding along the feed path upon the rotation of the feed roller; a controller in communication with the feed roller and including programming for monitoring rotation of the feed roller during a dispensing cycle for feeding a selected length of the sheet material from the supply of sheet material; a material supply monitoring system in communication with the controller and operable to detect a number of rotations or an angle of rotation of the supply sheet material during at least a series of dispensing cycles, the material supply monitoring system including a plurality of magnets (102, 104) that is rotatable with the supply (26, 27) of sheet material, and at least one sensor operable to measure or detect fluctuations or variations in a magnetic field created as the plurality of magnets (102, 104) is rotated or otherwise moves past the at least one sensor with the rotation of the supply of sheet material, and based upon the fluctuations or variations in the magnetic field, a remaining diameter of the supply of sheet material is substantially dynamically determined after at least each of the series of dispensing cycles; and a drive motor coupled to the feed roller and in communication with the controller, which controls operation of the drive motor to drive the rotation of the feed roller for feeding the selected length of sheet material; wherein the plurality of magnets is arranged to form magnetic ring with adjacent magnets of the plurality of magnets having opposite and alternating polarities.