BenchReference

#28 Drill Bit

Decimal inches 0.1405″
Millimeters 3.569 mm
System Number (wire gauge)

Nearest equivalents in other systems

System Nearest drill Size Difference
Metric 3.6 mm 0.1417″ / 3.6 mm +0.031 mm (+0.0012″)
Fractional inch 9/64″ 0.1406″ / 3.572 mm +0.003 mm (+0.0001″)
Letter A 0.2340″ / 5.944 mm +2.375 mm (+0.0935″)
−0.285 mm+0.285 mm#28#29−0.114 mm#27+0.089 mm#26+0.165 mm9/64″+0.003 mm3.6 mm+0.031 mm← #30 −0.305 mmA +2.375 mm →tick position = true diameter · number neighbors above, equivalents below · window ±0.29 mm
Positive difference = cuts a slightly larger hole than #28. Sizes beyond the window are listed with arrows — they are not close substitutes.

Neighboring number sizes

Drill Decimal in mm vs #28
#30 0.1285 3.264 −0.305 mm
#29 0.1360 3.454 −0.114 mm
#28 0.1405 3.569 —
#27 0.1440 3.658 +0.089 mm
#26 0.1470 3.734 +0.165 mm
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 number size is 0.1405″. See all data sources.