BenchReference

18.5 mm Drill

Decimal inches 0.7283″
Millimeters 18.5 mm
System Metric

Nearest equivalents in other systems

System Nearest drill Size Difference
Fractional inch 47/64″ 0.7344″ / 18.653 mm +0.153 mm (+0.0060″)
Number (wire gauge) #1 0.2280″ / 5.791 mm −12.709 mm (−0.5003″)
Letter Z 0.4130″ / 10.49 mm −8.01 mm (−0.3153″)
−1.48 mm+1.48 mm18.5 mm17.5 mm−1 mm18 mm−0.5 mm19 mm+0.5 mm19.5 mm+1 mm47/64″+0.153 mm← #1 −12.709 mm← Z −8.01 mmtick position = true diameter · metric neighbors above, equivalents below · window ±1.48 mm
Positive difference = cuts a slightly larger hole than 18.5 mm. Sizes beyond the window are listed with arrows — they are not close substitutes.

Tap drill for

Thread Major diameter Pitch
M20 × 1.5 0.7874″ / 20 mm 1.5 mm

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

Clearance drill for

Thread Fit
M16 × 2 loose
M16 × 1.5 loose

Neighboring metric sizes

Drill Decimal in mm vs 18.5 mm
17.5 mm 0.6890 17.5 −1 mm
18 mm 0.7087 18 −0.5 mm
18.5 mm 0.7283 18.5 —
19 mm 0.7480 19 +0.5 mm
19.5 mm 0.7677 19.5 +1 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 18.5 mm. See all data sources.