A method and device for monitoring toner transfer within an image forming device is described herein. A reflectivity sensor senses movement of a toner transfer gear operatively connected to a toner transfer system. A threshold unit generates a dynamic threshold based on the output of the reflectivity sensor. In one embodiment, the threshold unit generates the dynamic threshold based on a time delayed average of the sensor output. An instantaneous sensor output is compared to the dynamic threshold. Based on the comparison, the device determines the how much the toner transfer gear has rotated, and therefore, how much toner has been transferred from the toner cartridge.