BoltLabThread Identifier Tool
Quick answer
A thread identifier ranks likely standards from measured major diameter and pitch or TPI inputs.
It is a desk check before gauges, not a replacement for metrology on safety-critical joints.
Use the form below, then open tap drill size tools and screw size conversion when you pick hardware.
Bolt sizing and thread specifications follow widely recognized mechanical standards used in engineering and manufacturing. Standard bolt sizing references, industrial fastener charts, and mechanical thread standards ensure compatibility, safety, and correct tool selection across applications.
Identify metric or imperial threads by entering diameter and pitch, then compare candidates with thread types diagrams.
Match tap drill size outputs to the sizes you select here.
Identify thread standard
How matching works
This identifier checks your entered values against common thread standards—useful after screw identifier visual narrowing—and returns matches within diameter ±5% and pitch ±5%.
FAQ
How does the thread identifier choose matches?
The tool compares your measured diameter and pitch to known metric and imperial thread standards and returns options that fall within plus or minus 5 percent tolerance for both values.
Can I enter diameter in inches and pitch in TPI?
Yes. You can mix units. The tool normalizes values internally and updates likely matches instantly while you type.
Engineering references
After identifying a candidate thread, validate fit intent using Thread Engineering Reference, thread fit classes, and allowance vs tolerance.