BenchReference / Drill sizes / 1 mm 1 mm Drill Decimal inches 0.0394″
Millimeters 1 mm
System Metric
Nearest equivalents in other systems System Nearest drill Size Difference Fractional inch 3/64″ 0.0469″ / 1.191 mm +0.191 mm (+0.0075″)
Number (wire gauge) #61 0.0390″ / 0.991 mm −0.009 mm (−0.0004″)
Letter A 0.2340″ / 5.944 mm +4.944 mm (+0.1946″)
−0.15 mm +0.15 mm 1 mm 1.1 mm +0.1 mm #61 −0.009 mm 1.2 mm +0.2 mm → 3/64″ +0.191 mm → tick position = true diameter · metric neighbors above, equivalents below · window ±0.15 mm
Positive difference = cuts a slightly larger hole than 1 mm. Sizes
beyond the window are listed with arrows — they are not close substitutes.
Neighboring metric sizes Drill Decimal in mm vs 1 mm 1 mm 0.0394 1 — 1.1 mm 0.0433 1.1 +0.1 mm 1.2 mm 0.0472 1.2 +0.2 mm
1.1 mm (larger) →
Compare 1 mm 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 metric size is 1 mm. See all data sources .