fractional-inch drill · nominal diameter
1/2
drill bit size.
A 1/2 bit measures 0.5000 in across (12.700 mm).
The fractional diameter is exact; decimal and metric values are conversions.
Calibrated relative diameter · 1 in reference
1/2 · fractional
0.5000 in
12.700 mm Designation1/2fractional
Inch decimal0.5000nominal
Metric conversion12.700millimetres
Where this size sits from 0 to 1 inch 1/2 · 12.700 mm on a zero to 25.4 millimetre scale. Neighbor marks: 12.6 mm, 12.8 mm.
Measured neighbors
What sits beside 1/2.
“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