letter drill · nominal diameter

U
drill bit size.

A U bit measures 0.3680 in across (9.347 mm).

The inch decimal is the published nominal designation; millimetres are a conversion.

Diameter conversion cross-checked

Calibrated relative diameter · 1 in reference

U · letter

0.3680 in

9.347 mm

DesignationUletter

Inch decimal0.3680nominal

Metric conversion9.347millimetres

Where this size sits from 0 to 1 inch

U · 9.347 mm on a zero to 25.4 millimetre scale. Neighbor marks: 9.3 mm, 9.4 mm.

0 25.4 mm

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Measured neighbors

What sits beside U.

“Nearest” means nominal diameter only. It does not make a neighboring size acceptable for a tolerance, tapping, reaming, or fastener application.

Other naming systemsABSOLUTE DIAMETER DELTA

9.3 mmmetric 0.3661 inΔ -0.047 mm 9.4 mmmetric 0.3701 inΔ +0.053 mm 9.2 mmmetric 0.3622 inΔ -0.147 mm 9.5 mmmetric 0.3740 inΔ +0.153 mm 3/8fractional 0.3750 inΔ +0.178 mm

Same seriesNEAREST NOMINAL ROWS

Vletter 9.576 mmΔ +0.229 mm

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

Udrill bit size.

What sits beside U.

ASME.

U
drill bit size.