letter drill · nominal diameter

B
drill bit size.

A B bit measures 0.2380 in across (6.045 mm).

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

Diameter conversion cross-checked

Calibrated relative diameter · 1 in reference

B · letter

0.2380 in

6.045 mm

DesignationBletter

Inch decimal0.2380nominal

Metric conversion6.045millimetres

Where this size sits from 0 to 1 inch

B · 6.045 mm on a zero to 25.4 millimetre scale. Neighbor marks: 6 mm, 6.1 mm.

0 25.4 mm

Show calibrated outline Open in Finder

Measured neighbors

What sits beside B.

“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

6 mmmetric 0.2362 inΔ -0.045 mm 6.1 mmmetric 0.2402 inΔ +0.055 mm 15/64fractional 0.2344 inΔ -0.092 mm 5.9 mmmetric 0.2323 inΔ -0.145 mm 6.2 mmmetric 0.2441 inΔ +0.155 mm

Same seriesNEAREST NOMINAL ROWS

Aletter 5.944 mmΔ -0.102 mm Cletter 6.147 mmΔ +0.102 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

Bdrill bit size.

What sits beside B.

ASME.

B
drill bit size.