This paper describes a simple technique for evaluating refrigerant side pressure drop in mUlti-pass, plate-fin type evaporators common in the HVAC industry. The method of Thom forms the basis of the procedure with modifications to account for property index and arbitrary inlet quality. Experimental data has shown excellent accuracy down to mass velocities of 6.5 x 10 lbm/hr·ft² and as high as 3.0 x 10 5 lbm/hr·ft². The main advantage of the technique is that it is simple enough for hand calculations and can be programmed rapidly for use on a digital computer.