BenchReference

#7 Drill Bit

Decimal inches 0.2010″
Millimeters 5.105 mm
System Number (wire gauge)

Nearest equivalents in other systems

System Nearest drill Size Difference
Metric 5.1 mm 0.2008″ / 5.1 mm −0.005 mm (−0.0002″)
Fractional inch 13/64″ 0.2031″ / 5.159 mm +0.054 mm (+0.0021″)
Letter A 0.2340″ / 5.944 mm +0.838 mm (+0.0330″)
−0.408 mm+0.408 mm#7#9−0.127 mm#8−0.051 mm#6+0.076 mm#5+0.114 mm5.1 mm−0.005 mm13/64″+0.054 mmA +0.838 mm →tick position = true diameter · number neighbors above, equivalents below · window ±0.41 mm
Positive difference = cuts a slightly larger hole than #7. Sizes beyond the window are listed with arrows — they are not close substitutes.

Tap drill for

Thread Major diameter Pitch
1/4″-20 UNC 0.2500″ / 6.35 mm 20 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 #7
#9 0.1960 4.978 −0.127 mm
#8 0.1990 5.055 −0.051 mm
#7 0.2010 5.105 —
#6 0.2040 5.182 +0.076 mm
#5 0.2055 5.22 +0.114 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 0.2010″. See all data sources.