BenchReference / Drill sizes / 8.9 mm 8.9 mm Drill Decimal inches 0.3504″
Millimeters 8.9 mm
System Metric
Nearest equivalents in other systems System Nearest drill Size Difference Fractional inch 11/32″ 0.3438″ / 8.731 mm −0.169 mm (−0.0066″)
Number (wire gauge) #1 0.2280″ / 5.791 mm −3.109 mm (−0.1224″)
Letter S 0.3480″ / 8.839 mm −0.061 mm (−0.0024″)
−0.712 mm +0.712 mm 8.9 mm 8.7 mm −0.2 mm 8.8 mm −0.1 mm 9 mm +0.1 mm 9.1 mm +0.2 mm 11/32″ −0.169 mm S −0.061 mm ← #1 −3.109 mm tick position = true diameter · metric neighbors above, equivalents below · window ±0.71 mm
Positive difference = cuts a slightly larger hole than 8.9 mm. Sizes
beyond the window are listed with arrows — they are not close substitutes.
Neighboring metric sizes Drill Decimal in mm vs 8.9 mm 8.7 mm 0.3425 8.7 −0.2 mm 8.8 mm 0.3465 8.8 −0.1 mm 8.9 mm 0.3504 8.9 — 9 mm 0.3543 9 +0.1 mm 9.1 mm 0.3583 9.1 +0.2 mm
← 8.8 mm (smaller) 9 mm (larger) →
Compare 8.9 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 8.9 mm. See all data sources .