Covers recommendations for design calculations for conventional unit sucker rod pumping systems based on test dada submitted to API by Sucker Rod Pumping Research, Inc. The topics include vibration characteristics of sucker-rod strings, physical charecteristics of sucker rods and dimensional analysis of sucker-rod pumping systems. The calculations apply to the broad category of average, normal pumping wells fitting the assumed conditions defined therein. Unusual or out-of-the-ordinary conditions will cause deviations from calculated performance.