letter drill · nominal diameter

C
drill bit size.

A C bit measures 0.2420 in across (6.147 mm).

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

Diameter conversion cross-checked

Calibrated relative diameter · 1 in reference

C · letter

0.2420 in

6.147 mm

DesignationCletter

Inch decimal0.2420nominal

Metric conversion6.147millimetres

Where this size sits from 0 to 1 inch

C · 6.147 mm on a zero to 25.4 millimetre scale. Neighbor marks: 6.1 mm, 6.2 mm.

0 25.4 mm

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Measured neighbors

What sits beside C.

“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

6.1 mmmetric 0.2402 inΔ -0.047 mm 6.2 mmmetric 0.2441 inΔ +0.053 mm 6 mmmetric 0.2362 inΔ -0.147 mm 6.3 mmmetric 0.2480 inΔ +0.153 mm 15/64fractional 0.2344 inΔ -0.194 mm

Same seriesNEAREST NOMINAL ROWS

Dletter 6.248 mmΔ +0.102 mm Bletter 6.045 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

Cdrill bit size.

What sits beside C.

ASME.

C
drill bit size.