number drill · nominal diameter
#71
drill bit size.
A #71 bit measures 0.0260 in across (0.660 mm).
The inch decimal is the published nominal designation; millimetres are a conversion.
Calibrated relative diameter · 1 in reference
#71 · number
0.0260 in
0.660 mm Designation#71number
Inch decimal0.0260nominal
Metric conversion0.660millimetres
Where this size sits from 0 to 1 inch #71 · 0.660 mm on a zero to 25.4 millimetre scale. Neighbor marks: #72, 0.7 mm.
Measured neighbors
What sits beside #71.
“Nearest” means nominal diameter only. It does not make a neighboring size acceptable for a tolerance, tapping, reaming, or fastener application.
Source record
ASME.
The standard text is paywalled. Number and letter series are cross-checked against public manufacturer charts; exact standard edition/page verification remains a release gate.
Open source record