Abstract: In blood pressure measurement of a vertebrate through use of an inflatable pressure cuff disposed about a limb of the vertebrate limb and inflated by pump driven by a motor, the air pressure within the cuff is determined at any given time during the inflation of the cuff by calculating the incremental change in pressure in the pressure cuff over a series of small time increments and summing the calculated incremental pressure changes from the initiation of cuff inflation to a desired point in time during the inflation of the pressure cuff. The incremental change in pressure within the cuff is calculated as a function of the incremental change in current drawn by the pump motor over the time increment.