number drill · nominal diameter
#23
drill bit size.
A #23 bit measures 0.1540 in across (3.912 mm).
The inch decimal is the published nominal designation; millimetres are a conversion.
Calibrated relative diameter · 1 in reference
#23 · number
0.1540 in
3.912 mm Designation#23number
Inch decimal0.1540nominal
Metric conversion3.912millimetres
Where this size sits from 0 to 1 inch #23 · 3.912 mm on a zero to 25.4 millimetre scale. Neighbor marks: 3.9 mm, #24.
Measured neighbors
What sits beside #23.
“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