Everyone associated with quantity measurement has, at one time or another, asked himself the question, “Just how accurate is hand gaging?” Standard procedures and methods require reading the gage tape to the nearest ⅛ in. and the temperature to the nearest 1 F, but do not mention limits of accuracy. Accuracy is here defined as “freedom from mistake or error” and includes precision. Where do errors occur, what is their magnitude and probable occurrence, and what are the limitations of hand gaging as a standard? To answer these questions, some of the basic considerations in gaging will be reviewed and the results of some test programs the authors have conducted will be examined to determine the accuracy of gaging. Discussion will be limited to the determination of shore tank volumes. Measurement of quantities in marine carriers, tank cars, and tank trucks includes special considerations not involved here. Discussion is further limited to liquid level and temperature associated with bulk volume. Concern will not be given to the problems associated with the determination of gravity or water and sediment, although the calculated net volume of material may also depend on these tests. The results of gaging are influenced by the equipment and methods used and the environment under which the operations are carried out. A quick review of these factors might be helpful.