BenchReference / Drill sizes / K K Drill Bit Decimal inches 0.2810″
Millimeters 7.137 mm
System Letter
Nearest equivalents in other systems System Nearest drill Size Difference Metric 7.1 mm 0.2795″ / 7.1 mm −0.037 mm (−0.0015″)
Fractional inch 9/32″ 0.2813″ / 7.144 mm +0.006 mm (+0.0002″)
Number (wire gauge) #1 0.2280″ / 5.791 mm −1.346 mm (−0.0530″)
−0.571 mm +0.571 mm K I −0.229 mm J −0.102 mm L +0.229 mm M +0.356 mm 7.1 mm −0.037 mm 9/32″ +0.006 mm ← #1 −1.346 mm tick position = true diameter · letter neighbors above, equivalents below · window ±0.57 mm
Positive difference = cuts a slightly larger hole than K. Sizes
beyond the window are listed with arrows — they are not close substitutes.
Neighboring letter sizes Drill Decimal in mm vs K I 0.2720 6.909 −0.229 mm J 0.2770 7.036 −0.102 mm K 0.2810 7.137 — L 0.2900 7.366 +0.229 mm M 0.2950 7.493 +0.356 mm
← J (smaller) L (larger) →
Compare K 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 0.2810″. See all data sources .