fractional-inch drill · nominal diameter
1/8
drill bit size.
A 1/8 bit measures 0.1250 in across (3.175 mm).
The fractional diameter is exact; decimal and metric values are conversions.
Calibrated relative diameter · 1 in reference
1/8 · fractional
0.1250 in
3.175 mm Designation1/8fractional
Inch decimal0.1250nominal
Metric conversion3.175millimetres
Where this size sits from 0 to 1 inch 1/8 · 3.175 mm on a zero to 25.4 millimetre scale. Neighbor marks: 3.2 mm, 3.1 mm.
Measured neighbors
What sits beside 1/8.
“Nearest” means nominal diameter only. It does not make a neighboring size acceptable for a tolerance, tapping, reaming, or fastener application.
This row is at the exposed edge of its series.
Source record
Drill Bit Size Chart.
Fractional sizes are exact rational multiples of one inch.
Open source record