scope:

The purpose of 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.