In a series of 10 experiments, groups of Os judged the sweetness of 16 sugars. The results suggest that, for all sugars except mannose, the intensity of sweetness grows as a power function of concentration, with an exponent of about 1.3. The relative sweetness of sugars was determined using both molarity and per cent by weight. With both measures, sucrose and fructose were the sweetest sugars. The order of the remaining sugars in the sweetness hierarchy was partiy a function of the measure of concentration. The variability of the magnitude estimates of sweetness was roughly proportional to the stimulus concentration, supporting Weber’s law.