Taking the cylindrical gear meter that is used as master flow meter as an example, several typical flow calculation methods for the master flow meter used in the non-fixed point in the standard flow facility by master meter are introduced, and the uncertainty of each flow calculation method is evaluated. The comparison of the examples shows that using the least squares fitting calculation and selecting the fitting order matching the characteristics of the flowmeter can reduce the uncertainty introduced by the algorithm obviously, the method of selecting the flowrate correction value to calculate the flow rate is relatively inefficient for the low flow range, and the uncertainty introduced by using the meter factor is relatively close with that introduced by using the flow rate correction coefficient.