number drill · nominal diameter
#50
drill bit size.
A #50 bit measures 0.0700 in across (1.778 mm).
The inch decimal is the published nominal designation; millimetres are a conversion.
Calibrated relative diameter · 1 in reference
#50 · number
0.0700 in
1.778 mm Designation#50number
Inch decimal0.0700nominal
Metric conversion1.778millimetres
Where this size sits from 0 to 1 inch #50 · 1.778 mm on a zero to 25.4 millimetre scale. Neighbor marks: 1.8 mm, #49.
Measured neighbors
What sits beside #50.
“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