A method of filling by weight containers having respective bottoms standing on a conveyor, including the steps of: grasping each container in order to separate it from the conveyor and to bring it up to a substance dispenser spout; weighing the container while it is held separated from the conveyor under the dispenser spout and while simultaneously filling it in order to reach a desired weight; and putting the container back onto the conveyor. In addition, an installation for performing the above method is provided.