Abstract: An improved scale, and particularly an electronic postage scale, wherein a parcel is weighed and postage is computed automatically in accordance with the weight of the parcel and the particular class of shipment and destination zone therefor. It is one feature of this scale to determine a corrected reference level against which the parcel is weighed, notwithstanding changes in this reference level over a period of time due to, for example, parameter changes, electrical "drift," a build-up of particles, such as dirt or other residue, or the like. Another feature of this scale is improved, simplified automatic calibration. The scale is provided with a keyboard which, during a calibration operation, is selectively operated so as to key-in numerical data representing a standard weight. The keyed-in data is compared to the standard weight as actually measured by the scale, and a calibration factor is generated by dividing the keyed-in data by the measured standard weight.