In order to measure the degree of filling of a dust collector (5), where the dust (15, 16) collected in the dust collector may be of a very varied composition ranging from very fine dust (15) to rather large particles (16), a high pressure difference and a low pressure difference are measured by two differential pressure meters (11, 12), where the one differential pressure meter (12) measures the pressure difference between the compartment (4) of the dust collector, in which the dust collector (5) is arranged, and a measurement position at the connecting stub (6) of the vacuum cleaner, as is known, while the other differential pressure meter (11) measures between two measurement positions inside the connecting stub (6). Hereby, the method and the filling indicator according to the invention will ensure that larger particles do not settle inside the connecting stub (6) since these are detected beforehand by the differential pressure meter (11) which records lower pressure differences that the differential pressure meter (12).