The general formulation for the propagation of statistical uncertainties is presented for the dual volume pressure decay method of measuring sorption capacity in polymers and other solid sorbents. These relationships are then used to determine the percent uncertainty in the calculated sorption coefficient (or capacity) with respect to ranges of values for several parameters that relate to choices in equipment design and operating conditions, and properties of the sorbent. These parameters include the ratio of system volumes, the relative volume of the sorbent, the accuracy and resolution of the sensors, the operating pressure, and the nominal sorption capacity of the sorbent. This analysis provides guidance for determining the uncertainty in the calculated sorption capacity and minimizing that uncertainty within whatever logistical and resource constraints may exist.