BenchReference / Drill sizes / J J Drill Bit Decimal inches 0.2770″
Millimeters 7.036 mm
System Letter
Nearest equivalents in other systems System Nearest drill Size Difference Metric 7 mm 0.2756″ / 7 mm −0.036 mm (−0.0014″)
Fractional inch 9/32″ 0.2813″ / 7.144 mm +0.108 mm (+0.0042″)
Number (wire gauge) #1 0.2280″ / 5.791 mm −1.245 mm (−0.0490″)
−0.563 mm +0.563 mm J H −0.279 mm I −0.127 mm K +0.102 mm L +0.33 mm 7 mm −0.036 mm 9/32″ +0.108 mm ← #1 −1.245 mm tick position = true diameter · letter neighbors above, equivalents below · window ±0.56 mm
Positive difference = cuts a slightly larger hole than J. Sizes
beyond the window are listed with arrows — they are not close substitutes.
Neighboring letter sizes Drill Decimal in mm vs J H 0.2660 6.756 −0.279 mm I 0.2720 6.909 −0.127 mm J 0.2770 7.036 — K 0.2810 7.137 +0.102 mm L 0.2900 7.366 +0.33 mm
← I (smaller) K (larger) →
Compare J 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 0.2770″. See all data sources .