number drill · nominal diameter

#28
drill bit size.

A #28 bit measures 0.1405 in across (3.569 mm).

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

Diameter conversion cross-checked

Calibrated relative diameter · 1 in reference

#28 · number

0.1405 in

3.569 mm

Designation#28number

Inch decimal0.1405nominal

Metric conversion3.569millimetres

Where this size sits from 0 to 1 inch

#28 · 3.569 mm on a zero to 25.4 millimetre scale. Neighbor marks: 9/64, 3.6 mm.

0 25.4 mm

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Measured neighbors

What sits beside #28.

“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

9/64fractional 0.1406 inΔ +0.003 mm 3.6 mmmetric 0.1417 inΔ +0.031 mm 3.5 mmmetric 0.1378 inΔ -0.069 mm 3.7 mmmetric 0.1457 inΔ +0.131 mm 3.4 mmmetric 0.1339 inΔ -0.169 mm

Same seriesNEAREST NOMINAL ROWS

#27number 3.658 mmΔ +0.089 mm #29number 3.454 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

#28drill bit size.

What sits beside #28.

ASME.

#28
drill bit size.