BenchReference / Drill sizes / 31/32″ 31/32″ Drill Bit Decimal inches 0.9688″
Millimeters 24.606 mm
System Fractional inch
In 64ths 62/64″
Nearest equivalents in other systems System Nearest drill Size Difference Metric 21 mm 0.8268″ / 21 mm −3.606 mm (−0.1420″)
Number (wire gauge) #1 0.2280″ / 5.791 mm −18.815 mm (−0.7408″)
Letter Z 0.4130″ / 10.49 mm −14.116 mm (−0.5557″)
−1.968 mm +1.968 mm 31/32″ 15/16″ −0.794 mm 61/64″ −0.397 mm 63/64″ +0.397 mm 1″ +0.794 mm ← 21 mm −3.606 mm ← #1 −18.815 mm tick position = true diameter · fractional neighbors above, equivalents below · window ±1.97 mm
Positive difference = cuts a slightly larger hole than 31/32″. Sizes
beyond the window are listed with arrows — they are not close substitutes.
Neighboring fractional sizes Drill Decimal in mm vs 31/32″ 15/16″ 0.9375 23.813 −0.794 mm 61/64″ 0.9531 24.209 −0.397 mm 31/32″ 0.9688 24.606 — 63/64″ 0.9844 25.003 +0.397 mm 1″ 1.0000 25.4 +0.794 mm
← 61/64″ (smaller) 63/64″ (larger) →
Compare 31/32″ 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 0.9688″. See all data sources .