Which kind of diameter is used for measuring most fasteners?

The major diameter is the correct choice for measuring most fasteners, particularly when discussing external thread profiles such as those found on screws and bolts. This diameter represents the largest diameter of the threaded section, taking into account the peaks of the threads. It is crucial for the compatibility and fit of fasteners with corresponding nuts and threaded holes, as it ensures proper engagement and secure fastening.

Understanding the major diameter is essential for applications that require precise measurements to ensure structural integrity and performance. Fasteners are often specified using the major diameter to match with the tapped holes or to ensure proper assembly with the respective components. Fastener sizing and classification standards frequently reference the major diameter, affirming its importance in industry practices.