BenchReference / Drill sizes / 1/64″ 1/64″ Drill Bit Decimal inches 0.0156″
Millimeters 0.397 mm
System Fractional inch
Nearest equivalents in other systems System Nearest drill Size Difference Metric 1 mm 0.0394″ / 1 mm +0.603 mm (+0.0237″)
Number (wire gauge) #78 0.0160″ / 0.406 mm +0.01 mm (+0.0004″)
Letter A 0.2340″ / 5.944 mm +5.547 mm (+0.2184″)
−0.15 mm +0.15 mm 1/64″ #78 +0.01 mm 1/32″ +0.397 mm → 3/64″ +0.794 mm → tick position = true diameter · fractional neighbors above, equivalents below · window ±0.15 mm
Positive difference = cuts a slightly larger hole than 1/64″. Sizes
beyond the window are listed with arrows — they are not close substitutes.
Neighboring fractional sizes Drill Decimal in mm vs 1/64″ 1/64″ 0.0156 0.397 — 1/32″ 0.0313 0.794 +0.397 mm 3/64″ 0.0469 1.191 +0.794 mm
1/32″ (larger) →
Compare 1/64″ with another size
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 fractional size is 0.0156″. See all data sources .