letter drill · nominal diameter
T
drill bit size.
A T bit measures 0.3580 in across (9.093 mm).
The inch decimal is the published nominal designation; millimetres are a conversion.
Calibrated relative diameter · 1 in reference
T · letter
0.3580 in
9.093 mm DesignationTletter
Inch decimal0.3580nominal
Metric conversion9.093millimetres
Where this size sits from 0 to 1 inch T · 9.093 mm on a zero to 25.4 millimetre scale. Neighbor marks: 9.1 mm, 23/64.
Measured neighbors
What sits beside T.
“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