number drill · nominal diameter

#54
drill bit size.

A #54 bit measures 0.0550 in across (1.397 mm).

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

Diameter conversion cross-checked

Calibrated relative diameter · 1 in reference

#54 · number

0.0550 in

1.397 mm

Designation#54number

Inch decimal0.0550nominal

Metric conversion1.397millimetres

Where this size sits from 0 to 1 inch

#54 · 1.397 mm on a zero to 25.4 millimetre scale. Neighbor marks: 1.4 mm, #55.

0 25.4 mm

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Measured neighbors

What sits beside #54.

“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

1.4 mmmetric 0.0551 inΔ +0.003 mm 1.3 mmmetric 0.0512 inΔ -0.097 mm 1.5 mmmetric 0.0591 inΔ +0.103 mm 1/16fractional 0.0625 inΔ +0.190 mm 1.2 mmmetric 0.0472 inΔ -0.197 mm

Same seriesNEAREST NOMINAL ROWS

#55number 1.321 mmΔ -0.076 mm #53number 1.511 mmΔ +0.114 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

#54drill bit size.

What sits beside #54.

ASME.

#54
drill bit size.