BenchReference / Drill sizes / 61/64″ 61/64″ Drill Bit Decimal inches 0.9531″
Millimeters 24.209 mm
System Fractional inch
Nearest equivalents in other systems System Nearest drill Size Difference Metric 21 mm 0.8268″ / 21 mm −3.209 mm (−0.1264″)
Number (wire gauge) #1 0.2280″ / 5.791 mm −18.418 mm (−0.7251″)
Letter Z 0.4130″ / 10.49 mm −13.719 mm (−0.5401″)
−1.937 mm +1.937 mm 61/64″ 59/64″ −0.794 mm 15/16″ −0.397 mm 31/32″ +0.397 mm 63/64″ +0.794 mm ← 21 mm −3.209 mm ← #1 −18.418 mm tick position = true diameter · fractional neighbors above, equivalents below · window ±1.94 mm
Positive difference = cuts a slightly larger hole than 61/64″. Sizes
beyond the window are listed with arrows — they are not close substitutes.
Neighboring fractional sizes Drill Decimal in mm vs 61/64″ 59/64″ 0.9219 23.416 −0.794 mm 15/16″ 0.9375 23.813 −0.397 mm 61/64″ 0.9531 24.209 — 31/32″ 0.9688 24.606 +0.397 mm 63/64″ 0.9844 25.003 +0.794 mm
← 15/16″ (smaller) 31/32″ (larger) →
Compare 61/64″ with another size
Data provenance. ASME B94.11M, Twist Drills (standard drill size series) (ASME). Millimeter and inch values are converted with the exact definition 1 in = 25.4 mm; the canonical dimension for this fractional size is 0.9531″. See all data sources .