BenchReference / Drill sizes / Z Z Drill Bit Decimal inches 0.4130″
Millimeters 10.49 mm
System Letter
Nearest equivalents in other systems System Nearest drill Size Difference Metric 10.5 mm 0.4134″ / 10.5 mm +0.01 mm (+0.0004″)
Fractional inch 13/32″ 0.4063″ / 10.319 mm −0.171 mm (−0.0068″)
Number (wire gauge) #1 0.2280″ / 5.791 mm −4.699 mm (−0.1850″)
−0.839 mm +0.839 mm Z X −0.406 mm Y −0.229 mm 13/32″ −0.171 mm 10.5 mm +0.01 mm ← #1 −4.699 mm tick position = true diameter · letter neighbors above, equivalents below · window ±0.84 mm
Positive difference = cuts a slightly larger hole than Z. Sizes
beyond the window are listed with arrows — they are not close substitutes.
Neighboring letter sizes Drill Decimal in mm vs Z X 0.3970 10.084 −0.406 mm Y 0.4040 10.262 −0.229 mm Z 0.4130 10.49 —
← Y (smaller)
Compare Z 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 letter size is 0.4130″. See all data sources .