BenchReference / Drill sizes / 8.3 mm 8.3 mm Drill Decimal inches 0.3268″
Millimeters 8.3 mm
System Metric
Nearest equivalents in other systems System Nearest drill Size Difference Fractional inch 21/64″ 0.3281″ / 8.334 mm +0.034 mm (+0.0014″)
Number (wire gauge) #1 0.2280″ / 5.791 mm −2.509 mm (−0.0988″)
Letter P 0.3230″ / 8.204 mm −0.096 mm (−0.0038″)
−0.664 mm +0.664 mm 8.3 mm 8.1 mm −0.2 mm 8.2 mm −0.1 mm 8.4 mm +0.1 mm 8.5 mm +0.2 mm P −0.096 mm 21/64″ +0.034 mm ← #1 −2.509 mm tick position = true diameter · metric neighbors above, equivalents below · window ±0.66 mm
Positive difference = cuts a slightly larger hole than 8.3 mm. Sizes
beyond the window are listed with arrows — they are not close substitutes.
Neighboring metric sizes Drill Decimal in mm vs 8.3 mm 8.1 mm 0.3189 8.1 −0.2 mm 8.2 mm 0.3228 8.2 −0.1 mm 8.3 mm 0.3268 8.3 — 8.4 mm 0.3307 8.4 +0.1 mm 8.5 mm 0.3346 8.5 +0.2 mm
← 8.2 mm (smaller) 8.4 mm (larger) →
Compare 8.3 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 8.3 mm. See all data sources .