The invention provides a weighing device for a production machine or installation and a method for weighing piece goods from a production machine or installation, which can be implemented in a space-saving manner and/or permit processing of piece goods within a large belt width in the format of the piece goods. According to the invention, this is achieved in that the weight of two or more piece goods (7′, 7″) and the weight which is varied by subsequent feeding or discharge of an individual piece good (7″) or a number of piece goods to be jointly weighed are detected from which the weight of an individual piece good (7″) or a number of piece goods to be jointly weighed is determined from the difference between the weights.