Threads / Size reference

#6-32 UNC

#6-32 has a nominal outside diameter of 3.5052 mm and a 0.79375 mm pitch.

Nominal major diameter0.138 in

3.5052 mm

Threads per inch32 TPI

0.79375 mm pitch

Nominal dimensions; no class allowances or acceptance limits applied. The # prefix denotes a numbered screw, not millimetres.

#6-32 · PITCH VIEWSCHEMATIC
PP = 0.79375 mm · 32 TPI

same diameter comparison

#6-32 vs #6-40

#6-40 UNF shares the nominal diameter but has a 0.635000 mm pitch. The pitch difference is 0.158750 mm; these are different nominal threads.

Swipe to compare both sizes →

Nominal size comparison
Property#6-32 UNC#6-40 UNF
Nominal diameter · in0.1380.138
Nominal diameter · mm3.50523.5052
Threads per inchDifferent3240
Pitch · mmDifferent0.793750.635
Source chart available

Cutting-tap drill references

Cut taps · Guhring chart · PDF page 2
Target theoretical threadListed drillDiameter · in / mm
55%#320.116 / 2.9464
65%#340.111 / 2.8194
75%#360.1065 / 2.7051

Need acceptance limits?

The complete class and applicable drawing requirements are needed. These nominal values are not maximum/minimum inspection limits.

Part has no marking?

Measure the correct diameter and pitch, then compare candidates across metric and inch systems.

Basis for this size

Nominal designation and family transcribed from the live directory on 2026-10-19; unit conversions are calculated using exactly 25.4 mm/in. The drill row was read from Guhring PDF page 2; numbered and letter drill diameters use page 1. Paid standard limit tables have not been reviewed.

ASME B1.1 · standard scope ↗ · Guhring · Tap Drill Sizes ↗ Full source scope →