BenchReference

#77 Drill Bit

Decimal inches 0.0180″
Millimeters 0.457 mm
System Number (wire gauge)

Nearest equivalents in other systems

System Nearest drill Size Difference
Metric 1 mm 0.0394″ / 1 mm +0.543 mm (+0.0214″)
Fractional inch 1/64″ 0.0156″ / 0.397 mm −0.06 mm (−0.0024″)
Letter A 0.2340″ / 5.944 mm +5.486 mm (+0.2160″)
−0.15 mm+0.15 mm#77#79−0.089 mm#78−0.051 mm#76+0.051 mm#75+0.076 mm1/64″−0.06 mm1 mm +0.543 mm →A +5.486 mm →tick position = true diameter · number neighbors above, equivalents below · window ±0.15 mm
Positive difference = cuts a slightly larger hole than #77. Sizes beyond the window are listed with arrows — they are not close substitutes.

Neighboring number sizes

Drill Decimal in mm vs #77
#79 0.0145 0.368 −0.089 mm
#78 0.0160 0.406 −0.051 mm
#77 0.0180 0.457 —
#76 0.0200 0.508 +0.051 mm
#75 0.0210 0.533 +0.076 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 0.0180″. See all data sources.