BenchReference / Drill sizes / 2.1 mm 2.1 mm Drill Decimal inches 0.0827″
Millimeters 2.1 mm
System Metric
Nearest equivalents in other systems System Nearest drill Size Difference Fractional inch 5/64″ 0.0781″ / 1.984 mm −0.116 mm (−0.0046″)
Number (wire gauge) #45 0.0820″ / 2.083 mm −0.017 mm (−0.0007″)
Letter A 0.2340″ / 5.944 mm +3.844 mm (+0.1513″)
−0.168 mm +0.168 mm 2.1 mm 2 mm −0.1 mm 2.05 mm −0.05 mm 2.2 mm +0.1 mm 5/64″ −0.116 mm #45 −0.017 mm 2.3 mm +0.2 mm → A +3.844 mm → tick position = true diameter · metric neighbors above, equivalents below · window ±0.17 mm
Positive difference = cuts a slightly larger hole than 2.1 mm. Sizes
beyond the window are listed with arrows — they are not close substitutes.
Neighboring metric sizes Drill Decimal in mm vs 2.1 mm 2 mm 0.0787 2 −0.1 mm 2.05 mm 0.0807 2.05 −0.05 mm 2.1 mm 0.0827 2.1 — 2.2 mm 0.0866 2.2 +0.1 mm 2.3 mm 0.0906 2.3 +0.2 mm
← 2.05 mm (smaller) 2.2 mm (larger) →
Compare 2.1 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 2.1 mm. See all data sources .