本标准旨在为英制和公制螺纹设计数据尺寸所用数值的计算和四舍五入建立统一惯例。未尝试制定一项将螺纹量规制造商或用户测量的实际螺纹特性四舍五入的政策。涵盖了关于数值保留的最后一个数字或小数位以及螺纹尺寸中间计算中使用的数值保留的小数位的标准舍入政策。 附录中列出的一些值可能相差0.0001英寸。或与ASME B1螺纹标准之前版本中所示的值相差0.001 mm，且在所有未来的ASME B1标准中优先。

This standard is to establish uniform practices for calculating and rounding the numeric values used for inch and metric screw thread design data dimensions. No attempt is made to establish a policy of rounding actual thread characteristics measured by the manufacturer or user of thread gages. Covered is the standard rounding policy regarding the last figure or decimal place to be retained by a numeric value and the number of decimal places to be retained by values used in intermediate calculations of thread dimensions. Some values listed in the appendix may differ by as much as 0.0001 in. Or 0.001 mm from values shown in previous issues of ASME B1 Thread Standards and are to take precedence in all future ASME B1 standards.