Last updated: March 2, 2026

Understanding Thread Pitch

Formula

Thread pitch is the distance between adjacent threads, measured in threads per inch (TPI) for imperial or millimeters for metric fasteners.

The tap drill diameter is the hole size needed to cut internal threads. The clearance drill is the hole size that allows a bolt to pass through freely.

Common use cases:

  • Drilling tap holes for bolts
  • Identifying unknown fastener threads
  • Converting between metric and imperial threads

Frequently Asked Questions

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