Other naming systemsABSOLUTE DIAMETER DELTA
fractional-inch drill · nominal diameter
39/64
drill bit size.
A 39/64 bit measures 0.6094 in across (15.478 mm).
The fractional diameter is exact; decimal and metric values are conversions.
Calibrated relative diameter · 1 in reference
39/64 · fractional
0.6094 in
15.478 mm Designation39/64fractional
Inch decimal0.6094nominal
Metric conversion15.478millimetres
Where this size sits from 0 to 1 inch 39/64 · 15.478 mm on a zero to 25.4 millimetre scale. Neighbor marks: 19/32, 5/8.
Measured neighbors
What sits beside 39/64.
“Nearest” means nominal diameter only. It does not make a neighboring size acceptable for a tolerance, tapping, reaming, or fastener application.
Source record
Drill Bit Size Chart.
Fractional sizes are exact rational multiples of one inch.
Open source record