metric comparison size · nominal diameter
3.1 mm
drill bit size.
A 3.1 mm bit measures 0.1220 in across (3.100 mm).
The metric diameter is the generated reference value; inches are a conversion. Commercial set contents vary.
Calibrated relative diameter · 1 in reference
3.1 mm · metric
0.1220 in
3.100 mm Designation3.1 mmmetric
Inch decimal0.1220nominal
Metric conversion3.100millimetres
Where this size sits from 0 to 1 inch 3.1 mm · 3.100 mm on a zero to 25.4 millimetre scale. Neighbor marks: #31, 1/8.
Measured neighbors
What sits beside 3.1 mm.
“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.
A generated comparison series from 0.5 to 13.0 mm in 0.1 mm steps. It is not a claim that every size is included in every commercial set.
Open source record