BenchReference

#51 Drill Bit

Decimal inches 0.0670″
Millimeters 1.702 mm
System Number (wire gauge)

Nearest equivalents in other systems

System Nearest drill Size Difference
Metric 1.7 mm 0.0669″ / 1.7 mm −0.002 mm (−0.0001″)
Fractional inch 1/16″ 0.0625″ / 1.587 mm −0.114 mm (−0.0045″)
Letter A 0.2340″ / 5.944 mm +4.242 mm (+0.1670″)
−0.15 mm+0.15 mm#51#52−0.089 mm#50+0.076 mm1/16″−0.114 mm1.7 mm−0.002 mm← #53 −0.191 mm#49 +0.152 mm →A +4.242 mm →tick position = true diameter · number neighbors above, equivalents below · window ±0.15 mm
Positive difference = cuts a slightly larger hole than #51. Sizes beyond the window are listed with arrows — they are not close substitutes.

Clearance drill for

Thread Fit
#0-80 UNF close

Neighboring number sizes

Drill Decimal in mm vs #51
#53 0.0595 1.511 −0.191 mm
#52 0.0635 1.613 −0.089 mm
#51 0.0670 1.702 —
#50 0.0700 1.778 +0.076 mm
#49 0.0730 1.854 +0.152 mm
Data provenance. ASME B94.11M, Twist Drills (standard drill size series) (ASME). Millimeter and inch values are converted with the exact definition 1 in = 25.4 mm; the canonical dimension for this number size is 0.0670″. See all data sources.