For the calculation and measurement between pins in the external helical gears with an odd number of teeth, they have been studied for many years. And the calculation methods and measurements are also described in DIN and AGMA standards. However, for ISO standard, a clear conclusion has not been given yet. The differences between the research results and standards are still inconsistent in some cases of the actual situation. In the actual measurements, the pin instead of the ball is always used by survey crew. It is unreasonable that an incorrect value (usually the value across the ball) and measuring methods are used. In this paper, different calculations and measuring methods of different standards are firstly expressed. For different measurement tools, like dial caliper, outside micrometer and disc micrometer, the measurement results are not the same. Therefore, two test gears were manufactured and analyzed to verify the accuracy and reliability of the measurement methods between software calculation and manual measurement over pins. It is found that the calculation and measurement methods of DIN, AGMA or similar methods are feasible and reliable, but for the measuring surface of the measuring tools, the pin should be in a steady state along the spiral groove. Reliable measurement values are obtained to ensure the accuracy of the measurement. It is helpful to understand the measurements of the standard or similar methods through theoretical analysis and experiments.