Unified Thread Calculator

TAPPING & THREADING
Tap Drill Diameter
Pitch Diameter
Minor Diameter
Pitch = 1/TPI. Tap Drill ≈ Major Dia − (1.0825/TPI). Pitch Dia = Major Dia − 0.6495/TPI. Minor Dia = Major Dia − 1.0825/TPI.

Spotted an error or have a suggestion for this calculator? Let us know →
Scroll to Top

The calculators and tools on Formula Factory are provided for general guidance and informational purposes only. Results are estimates based on standard formulas and the values you enter — they do not constitute professional engineering, electrical, or architectural advice. Always verify calculations with a qualified professional before making decisions for any safety-critical, code-compliance, or commercial application. Formula Factory makes no representations or warranties as to the accuracy or completeness of any result, and accepts no liability for errors, omissions, or any outcomes arising from reliance on this information.