Abstract: Vertical metal tanks (hereinafter referred to as vertical tanks) are a measurement instrument that requires compulsory verification. The measurement accuracy directly relates to trading parties’ economic interests. This paper discusses factors affecting accuracy of volume measurements of vertical metal tanks, including the incident angle’s effect (no more than 60°) in total station surveying, the correlation between inputs in uncertainty evaluation for radial deviation measurements, the strapping method for measuring the base circle, and dealing with the outliers when fitting the measurement center and radius.