Find the size.
See how it lines up.
Sourced dimensions and tapping relationships, ready to read. Every table connects to the same physical axis.
Metric tap-drill chart
Choose the full thread designation, including pitch. These cutting-tap recommendations belong to that exact thread, not just its major diameter.
Open reference TappingUNC tap-drill chart
Find a Unified National Coarse thread by its diameter and threads per inch. Each drill value is the source’s cutting-tap recommendation.
Open reference TappingUNF tap-drill chart
Find a Unified National Fine thread by its diameter and threads per inch. A different pitch can require a different hole, even at the same major diameter.
Open reference DimensionsDrill size chart
Read each drill’s cutting diameter in millimetres and inches. Number and letter designations are catalogue names, not measurement units.
Open reference DimensionsFractional inches to millimetres
Every sixty-fourth from 1/64″ through 1″, reduced to its simplest fraction. One inch is exactly 25.4 mm, so these displayed conversions are exact.
Open reference ThreadsBSP thread dimensions
A pipe’s nominal size is not its physical thread diameter. Check the prefix as well as the size: G, R, Rp and Rc represent different thread forms and roles.
Open referenceThread-specific tapping references
The full designation matters. These pages keep the pitch, major diameter and recommended hole together.
Thread pitch, profile, tolerances and the mating standard still matter. Pipe designations are nominal names. Tapping recommendations describe a hole for a particular thread.
Read the sources and measurement definitions