Disclosed is a dosage device for determining the number of remaining doses of medication available in a medical inhaler, comprising a sensitive electronic weigh scale capable of recording measurements at least as small as 0.001 grams for providing an output signal dependent on the weight of a medical inhaler, or the canister of a medical inhaler, placed on the weigh scale a memory containing a data structure in the form of a table storing shot weight, new inhaler weight, tare weight and total number of doses for each of a plurality of different medical inhalers and input device for permitting a user to select one of said plurality of medical inhalers a processor configured to read the shot weight, new inhaler weight, tare weight, and total number of doses from said memory for the selected medical inhaler, and said processor being configured to calculate the number of doses remaining in the medical inhaler by either: determining the weight as sensed by said weigh scale, subtracting the weight of a new inhaler from the measured weight, and dividing the resulting weight by the shot weight, the result of which is then added to the number of doses or by determining the weight as sensed by said weigh scale, subtracting the tare weight, and dividing the resulting net weight by the shot weight and a display device configured to display the remaining number of doses determined by said processor.
