BenchReference

#33 Drill Bit

Decimal inches 0.1130″
Millimeters 2.87 mm
System Number (wire gauge)

Nearest equivalents in other systems

System Nearest drill Size Difference
Metric 2.9 mm 0.1142″ / 2.9 mm +0.03 mm (+0.0012″)
Fractional inch 7/64″ 0.1094″ / 2.778 mm −0.092 mm (−0.0036″)
Letter A 0.2340″ / 5.944 mm +3.073 mm (+0.1210″)
−0.23 mm+0.23 mm#33#35−0.076 mm#34−0.051 mm#32+0.076 mm#31+0.178 mm7/64″−0.092 mm2.9 mm+0.03 mmA +3.073 mm →tick position = true diameter · number neighbors above, equivalents below · window ±0.23 mm
Positive difference = cuts a slightly larger hole than #33. Sizes beyond the window are listed with arrows — they are not close substitutes.

Tap drill for

Thread Major diameter Pitch
#6-40 UNF 0.1380″ / 3.505 mm 40 TPI

The standard chart recommendation (≈75% thread engagement). Application-specific factors — material, hole depth, tap type — can justify a different drill.

Neighboring number sizes

Drill Decimal in mm vs #33
#35 0.1100 2.794 −0.076 mm
#34 0.1110 2.819 −0.051 mm
#33 0.1130 2.87 —
#32 0.1160 2.946 +0.076 mm
#31 0.1200 3.048 +0.178 mm
Data provenance. ASME B94.11M, Twist Drills (standard drill size series) (ASME). Machinery’s Handbook — tap drill charts (Industrial Press). Millimeter and inch values are converted with the exact definition 1 in = 25.4 mm; the canonical dimension for this number size is 0.1130″. See all data sources.