10.2 mm Drill

Decimal inches 0.4016″

Millimeters 10.2 mm

System Metric

Nearest equivalents in other systems

System	Nearest drill	Size	Difference
Fractional inch	13/32″	0.4063″ / 10.319 mm	+0.119 mm (+0.0047″)
Number (wire gauge)	#1	0.2280″ / 5.791 mm	−4.409 mm (−0.1736″)
Letter	Y	0.4040″ / 10.262 mm	+0.062 mm (+0.0024″)

Positive difference = cuts a slightly larger hole than 10.2 mm. Sizes beyond the window are listed with arrows — they are not close substitutes.

Tap drill for

Thread	Major diameter	Pitch
M12 × 1.75	0.4724″ / 12 mm	1.75 mm

The standard chart recommendation (≈75% thread engagement). Application-specific factors — material, hole depth, tap type — can justify a different drill.

Neighboring metric sizes

Drill	Decimal in	mm	vs 10.2 mm
10 mm	0.3937	10	−0.2 mm
10.1 mm	0.3976	10.1	−0.1 mm
10.2 mm	0.4016	10.2	—
10.3 mm	0.4055	10.3	+0.1 mm
10.4 mm	0.4094	10.4	+0.2 mm

Data provenance. ASME B94.11M, Twist Drills (standard drill size series) (ASME). Machinery’s Handbook — tap drill charts (Industrial Press). Millimeter and inch values are converted with the exact definition 1 in = 25.4 mm; the canonical dimension for this metric size is 10.2 mm. See all data sources.