Universal calculator

Tap drill, clearance, and pitch diameter.

Pick a standard and a nominal size, then move the thread engagement slider. Every result -- tap drill, clearance drill, pitch diameter, minor diameter -- recomputes instantly from the same basic-dimension formulas behind every chart on this site.

Thread spec

Nominal size

Thread engagement

75%

Clearance fit

NPT is tapered: engagement here depends on how far the joint is driven onto the taper, not diameter alone. Treat this as a straight-thread approximation and check ANSI/ASME B1.20.1 or your tap manufacturer’s chart before cutting production parts.

Calculated live

Tap drillJ0.2764" calculated · J (0.2764") nearest standard

Pitch: 0.0370"
Pitch diameter (basic): 0.2884"
Minor diameter (basic): 0.2644"
Clearance drill (normal): 11/32" (0.3438")