BenchReference / Drill sizes / 8.6 mm 8.6 mm Drill Decimal inches 0.3386″
Millimeters 8.6 mm
System Metric
Nearest equivalents in other systems System Nearest drill Size Difference Fractional inch 11/32″ 0.3438″ / 8.731 mm +0.131 mm (+0.0052″)
Number (wire gauge) #1 0.2280″ / 5.791 mm −2.809 mm (−0.1106″)
Letter R 0.3390″ / 8.611 mm +0.011 mm (+0.0004″)
−0.688 mm +0.688 mm 8.6 mm 8.4 mm −0.2 mm 8.5 mm −0.1 mm 8.7 mm +0.1 mm 8.8 mm +0.2 mm R +0.011 mm 11/32″ +0.131 mm ← #1 −2.809 mm tick position = true diameter · metric neighbors above, equivalents below · window ±0.69 mm
Positive difference = cuts a slightly larger hole than 8.6 mm. Sizes
beyond the window are listed with arrows — they are not close substitutes.
Neighboring metric sizes Drill Decimal in mm vs 8.6 mm 8.4 mm 0.3307 8.4 −0.2 mm 8.5 mm 0.3346 8.5 −0.1 mm 8.6 mm 0.3386 8.6 — 8.7 mm 0.3425 8.7 +0.1 mm 8.8 mm 0.3465 8.8 +0.2 mm
← 8.5 mm (smaller) 8.7 mm (larger) →
Compare 8.6 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 8.6 mm. See all data sources .