Tap Drill / Thread Calculator
Find recommended tap drill sizes for common metric, UNC, UNF, and NPT threads. This page helps engineers and buyers sanity-check threaded hole callouts before CNC machining and RFQ.
Covers
Metric, UNC, UNF, NPT
Shows
Tap drill, pitch, major diameter, notes
Best For
Design checks before machining RFQ
Choose a thread standard
This calculator is designed for common internal tapped hole planning. Always verify against your project standard and thread class before release.
Selected Thread
Loading thread data
Choose a thread family and size to show the recommended tap drill information.
Engineering Note
What this calculator is best used for
This page is ideal for quick thread sanity checks during DFM review, quoting, and drawing prep. It helps reduce small but expensive CNC mistakes like wrong pilot holes, poor thread engagement assumptions, or incorrect pipe-thread callouts.
Before RFQ
Use it to check whether your tapped hole callout looks realistic before sending drawings.
During DFM
Helpful when reviewing wall thickness, thread depth, or whether a fluid port should be NPT instead of a machine thread.
For Production
Good for fast communication with machinists when confirming tap size, drill prep, and common thread standards.