This paper describes measurement of velocity data used for the determination of K-factors for the rotary vane anemometer when used with finned tube coils. The K-factor is the true face velocity divided by the averaged face velocity obtained using rotary vane anemometer readings. Seven assorted coils, each with a face area 6 ft2 (0.557 m2) were tested with variations in rows of tubes (2, 4, and 8), fins per inch (5, 10, and 14) (197, 394, and 551 fins per meter), and tube outside diameters (5/8 in., 3/4 in., and 1.05 in.) (15.87, 19.05, and 26.67 mm). For each coil two sets of nineteen readings were taken on the downstream face. The second set of readings was taken with the anemometer vertically displaced one-half of tube spacing. The K-factor was a function of the rows of tubes, fin spacing, tube diameter, and the true face velocity and varied from 0.67 to 0.81.