Detecting a tool used on a touch screen. In accordance with a method embodiment of the present invention, a cell value is accessed for each cell of a touch sensing device. The cell value indicates a force applied to the cell. A touch area sample count is determined as a count of how many of the cells have a cell value above a noise floor. A touch area weight is determined as a sum of all cell values for the cells having a cell value above the noise floor. An object touching the touch sensing device is identified based on the touch area sample count and the touch area weight. The object's touch indication may be rejected if the object is not identified. The identity of the object may be reported to a software application.