The invention relates to a device for determining the weight of a hydraulic accumulator (10) during the operation thereof in a hydraulic facility, where a pressurised liquid is introduced into a pressure vessel at least partially filled with a gas, said pressurised liquid compressing the gas and being stored in such a way that when it leaves the accumulator (10), hydraulic energy is emitted to the facility, and where the respective current weight of the hydraulic accumulator (10) is detected by means of a weighing device (14) applied to the hydraulic accumulator (10).