BenchReference / Drill sizes / 3/8″ 3/8″ Drill Bit Decimal inches 0.3750″
Millimeters 9.525 mm
System Fractional inch
In 64ths 24/64″
Nearest equivalents in other systems System Nearest drill Size Difference Metric 9.5 mm 0.3740″ / 9.5 mm −0.025 mm (−0.0010″)
Number (wire gauge) #1 0.2280″ / 5.791 mm −3.734 mm (−0.1470″)
Letter V 0.3770″ / 9.576 mm +0.051 mm (+0.0020″)
−0.762 mm +0.762 mm 3/8″ 23/64″ −0.397 mm 25/64″ +0.397 mm 9.5 mm −0.025 mm V +0.051 mm ← 11/32″ −0.794 mm ← #1 −3.734 mm 13/32″ +0.794 mm → tick position = true diameter · fractional neighbors above, equivalents below · window ±0.76 mm
Positive difference = cuts a slightly larger hole than 3/8″. Sizes
beyond the window are listed with arrows — they are not close substitutes.
Neighboring fractional sizes Drill Decimal in mm vs 3/8″ 11/32″ 0.3438 8.731 −0.794 mm 23/64″ 0.3594 9.128 −0.397 mm 3/8″ 0.3750 9.525 — 25/64″ 0.3906 9.922 +0.397 mm 13/32″ 0.4063 10.319 +0.794 mm
← 23/64″ (smaller) 25/64″ (larger) →
Compare 3/8″ 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 0.3750″. See all data sources .