number drill · nominal diameter

#16
drill bit size.

A #16 bit measures 0.1770 in across (4.496 mm).

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

Diameter conversion cross-checked

Calibrated relative diameter · 1 in reference

#16 · number

0.1770 in

4.496 mm

Designation#16number

Inch decimal0.1770nominal

Metric conversion4.496millimetres

Where this size sits from 0 to 1 inch

#16 · 4.496 mm on a zero to 25.4 millimetre scale. Neighbor marks: 4.5 mm, #15.

0 25.4 mm

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Measured neighbors

What sits beside #16.

“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

4.5 mmmetric 0.1772 inΔ +0.004 mm 4.4 mmmetric 0.1732 inΔ -0.096 mm 4.6 mmmetric 0.1811 inΔ +0.104 mm 11/64fractional 0.1719 inΔ -0.130 mm

Same seriesNEAREST NOMINAL ROWS

#15number 4.572 mmΔ +0.076 mm #17number 4.394 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

#16drill bit size.

What sits beside #16.

ASME.

#16
drill bit size.