BenchReference

#45 Drill Bit

Decimal inches 0.0820″
Millimeters 2.083 mm
System Number (wire gauge)

Nearest equivalents in other systems

System Nearest drill Size Difference
Metric 2.1 mm 0.0827″ / 2.1 mm +0.017 mm (+0.0007″)
Fractional inch 5/64″ 0.0781″ / 1.984 mm −0.098 mm (−0.0039″)
Letter A 0.2340″ / 5.944 mm +3.861 mm (+0.1520″)
−0.167 mm+0.167 mm#45#47−0.089 mm#46−0.025 mm#44+0.102 mm5/64″−0.098 mm2.1 mm+0.017 mm#43 +0.178 mm →A +3.861 mm →tick position = true diameter · number neighbors above, equivalents below · window ±0.17 mm
Positive difference = cuts a slightly larger hole than #45. Sizes beyond the window are listed with arrows — they are not close substitutes.

Tap drill for

Thread Major diameter Pitch
#3-56 UNF 0.0990″ / 2.515 mm 56 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 #45
#47 0.0785 1.994 −0.089 mm
#46 0.0810 2.057 −0.025 mm
#45 0.0820 2.083 —
#44 0.0860 2.184 +0.102 mm
#43 0.0890 2.261 +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 0.0820″. See all data sources.