BenchReference / Drill sizes / 10.3 mm 10.3 mm Drill Decimal inches 0.4055″
Millimeters 10.3 mm
System Metric
Nearest equivalents in other systems System Nearest drill Size Difference Fractional inch 13/32″ 0.4063″ / 10.319 mm +0.019 mm (+0.0007″)
Number (wire gauge) #1 0.2280″ / 5.791 mm −4.509 mm (−0.1775″)
Letter Y 0.4040″ / 10.262 mm −0.038 mm (−0.0015″)
−0.824 mm +0.824 mm 10.3 mm 10.1 mm −0.2 mm 10.2 mm −0.1 mm 10.4 mm +0.1 mm 10.5 mm +0.2 mm Y −0.038 mm 13/32″ +0.019 mm ← #1 −4.509 mm tick position = true diameter · metric neighbors above, equivalents below · window ±0.82 mm
Positive difference = cuts a slightly larger hole than 10.3 mm. Sizes
beyond the window are listed with arrows — they are not close substitutes.
Neighboring metric sizes Drill Decimal in mm vs 10.3 mm 10.1 mm 0.3976 10.1 −0.2 mm 10.2 mm 0.4016 10.2 −0.1 mm 10.3 mm 0.4055 10.3 — 10.4 mm 0.4094 10.4 +0.1 mm 10.5 mm 0.4134 10.5 +0.2 mm
← 10.2 mm (smaller) 10.4 mm (larger) →
Compare 10.3 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 10.3 mm. See all data sources .