Other naming systemsABSOLUTE DIAMETER DELTA
fractional-inch drill · nominal diameter
13/16
drill bit size.
A 13/16 bit measures 0.8125 in across (20.637 mm).
The fractional diameter is exact; decimal and metric values are conversions.
Calibrated relative diameter · 1 in reference
13/16 · fractional
0.8125 in
20.637 mm Designation13/16fractional
Inch decimal0.8125nominal
Metric conversion20.637millimetres
Where this size sits from 0 to 1 inch 13/16 · 20.637 mm on a zero to 25.4 millimetre scale. Neighbor marks: 53/64, 51/64.
Measured neighbors
What sits beside 13/16.
“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