#50 Drill Bit

Decimal inches 0.0700″

Millimeters 1.778 mm

System Number (wire gauge)

Nearest equivalents in other systems

System	Nearest drill	Size	Difference
Metric	1.8 mm	0.0709″ / 1.8 mm	+0.022 mm (+0.0009″)
Fractional inch	1/16″	0.0625″ / 1.587 mm	−0.191 mm (−0.0075″)
Letter	A	0.2340″ / 5.944 mm	+4.166 mm (+0.1640″)

Positive difference = cuts a slightly larger hole than #50. Sizes beyond the window are listed with arrows — they are not close substitutes.

Tap drill for

Thread	Major diameter	Pitch
#2-56 UNC	0.0860″ / 2.184 mm	56 TPI
#2-64 UNF	0.0860″ / 2.184 mm	64 TPI

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

Neighboring number sizes

Drill	Decimal in	mm	vs #50
#52	0.0635	1.613	−0.165 mm
#51	0.0670	1.702	−0.076 mm
#50	0.0700	1.778	—
#49	0.0730	1.854	+0.076 mm
#48	0.0760	1.93	+0.152 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 number size is 0.0700″. See all data sources.