number drill · nominal diameter

#30
drill bit size.

A #30 bit measures 0.1285 in across (3.264 mm).

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

Diameter conversion cross-checked

Calibrated relative diameter · 1 in reference

#30 · number

0.1285 in

3.264 mm

Designation#30number

Inch decimal0.1285nominal

Metric conversion3.264millimetres

Where this size sits from 0 to 1 inch

#30 · 3.264 mm on a zero to 25.4 millimetre scale. Neighbor marks: 3.3 mm, 3.2 mm.

0 25.4 mm

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Measured neighbors

What sits beside #30.

“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

3.3 mmmetric 0.1299 inΔ +0.036 mm 3.2 mmmetric 0.1260 inΔ -0.064 mm 1/8fractional 0.1250 inΔ -0.089 mm 3.4 mmmetric 0.1339 inΔ +0.136 mm 3.1 mmmetric 0.1220 inΔ -0.164 mm

Same seriesNEAREST NOMINAL ROWS

#29number 3.454 mmΔ +0.191 mm #31number 3.048 mmΔ -0.216 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

#30drill bit size.

What sits beside #30.

ASME.

#30
drill bit size.