BenchReference

59/64″ Drill Bit

Decimal inches 0.9219″
Millimeters 23.416 mm
System Fractional inch

Nearest equivalents in other systems

System Nearest drill Size Difference
Metric 21 mm 0.8268″ / 21 mm −2.416 mm (−0.0951″)
Number (wire gauge) #1 0.2280″ / 5.791 mm −17.624 mm (−0.6939″)
Letter Z 0.4130″ / 10.49 mm −12.925 mm (−0.5089″)
−1.873 mm+1.873 mm59/64″57/64″−0.794 mm29/32″−0.397 mm15/16″+0.397 mm61/64″+0.794 mm← 21 mm −2.416 mm← #1 −17.624 mmtick position = true diameter · fractional neighbors above, equivalents below · window ±1.87 mm
Positive difference = cuts a slightly larger hole than 59/64″. Sizes beyond the window are listed with arrows — they are not close substitutes.

Tap drill for

Thread Major diameter Pitch
1″-12 UNF 1.0000″ / 25.4 mm 12 TPI

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

Neighboring fractional sizes

Drill Decimal in mm vs 59/64″
57/64″ 0.8906 22.622 −0.794 mm
29/32″ 0.9063 23.019 −0.397 mm
59/64″ 0.9219 23.416 —
15/16″ 0.9375 23.813 +0.397 mm
61/64″ 0.9531 24.209 +0.794 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 fractional size is 0.9219″. See all data sources.