Abstract: Method and device for determining the seal quality of packages, such as bags partially filled with products and protective gas. To this end these bags are directed between two opposing conveyors, the distance between these conveyors being less than the height of the packages, so that these are compressed. By taking measurements at one or two locations a verdict can be given on the seal quality of the packages. With this arrangement one of the conveyors is set up so that it can be moved relative to the other in order to ensure a more or less constant pressure on the packages. In order to achieve an accurate measurement it is proposed to measure the displacement resulting from this pressing on the packages at the conveyor that can be moved, using as reference the sub-frame of the conveyor that cannot be moved.