Method for processing containers, wherein the containers being transported along a predefined transport path and being combined with at least one product that can be defined in terms of its amount, that the product is supplied to each individual container in a predetermined supply region of the transport path, wherein the product being guided to the supply region along a supply path, wherein in a detection region, which is arranged along the supply path of the product or upstream of the supply region in a transport direction of the containers, at least one characteristic state which is individually determined, in particular prior to the processing, and at least one further characteristic state (Zw) is determined by a detection unit, which characteristic state and which further characteristic state (Zw) is characteristic of an output fitting amount of the product to be supplied in relation to at least one fitting device, and wherein the further characteristic state (Zw) is calculated by the detection unit such that a mathematical average of the characteristic state and of an expected value not determined by the detection unit, is determined, wherein the expected value being assigned, preferably uniquely, to the particular product and/or the particular fitting device and the expected value in relation to the respective fitting device is a value specified by the manufacturer, and wherein a remaining amount of the product to be supplied, on the fitting device, being determined on the basis of said characteristic state and said further characteristic state (Zw) during operation, and wherein a characteristic signal for a fitting changeover being emitted on the basis of said remaining amount, wherein the product is a labelling or packaging material, wherein this characteristic state is determined individually in each case by the detection unit, before the actual processing of the containers, instead of being fixedly predefined, so as to therefore know in advance how many labels, for example, are in principle available for a labelling process. in a detection region, which is arranged along the supply path of the product or upstream of the supply region in a transport direction of the containers, at least one characteristic state which is individually determined, in particular prior to the processing, and at least one further characteristic state (Zw) is determined by a detection unit, which characteristic state and which further characteristic state (Zw) is characteristic of an output fitting amount of the product to be supplied in relation to at least one fitting device, and wherein the further characteristic state (Zw) is calculated by the detection unit such that a mathematical average of the characteristic state and of an expected value not determined by the detection unit, is determined, wherein the expected value being assigned, preferably uniquely, to the particular product and/or the particular fitting device and the expected value in relation to the respective fitting device is a value specified by the manufacturer, and wherein a remaining amount of the product to be supplied, on the fitting device, being determined on the basis of said characteristic state and said further characteristic state (Zw) during operation, and wherein a characteristic signal for a fitting changeover being emitted on the basis of said remaining amount, wherein the product is a labelling or packaging material, wherein this characteristic state is determined individually in each case by the detection unit, before the actual processing of the containers, instead of being fixedly predefined, so as to therefore know in advance how many labels, for example, are in principle available for a labelling process.