The relation between tone frequency and position of stimulation on the basilar membrane has been calculated from data on differential pitch sensitivity. The calculations involve assumptions concerning the choice of the upper and lower pitch limits of hearing and the choice of tone levels which should be used in obtaining differential pitch sensitivity data. It is shown that for quite different assumptions the positions of stimulation for tones in the range from 500 to 10,000 cycles are not greatly affected. Outside this range the positions depend on the assumptions. The calculated positions for tones of 1000, 2000 and 4000 cycles fall, respectively, at points on the membrane about 13, 12 and 23 of its length away from the helicotrema. The calculated positions are compared with positions obtained from post-mortem studies of human cochlea and with positions obtained from electric response measurements on the cochlea of anesthetized guinea pigs. The differences between various methods for the most part are no larger than calculated differences between observers.