number drill · nominal diameter

#1
drill bit size.

A #1 bit measures 0.2280 in across (5.791 mm).

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

Diameter conversion cross-checked

Calibrated relative diameter · 1 in reference

#1 · number

0.2280 in

5.791 mm

Designation#1number

Inch decimal0.2280nominal

Metric conversion5.791millimetres

Where this size sits from 0 to 1 inch

#1 · 5.791 mm on a zero to 25.4 millimetre scale. Neighbor marks: 5.8 mm, 5.7 mm.

0 25.4 mm

Show calibrated outline Open in Finder

Measured neighbors

What sits beside #1.

“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

5.8 mmmetric 0.2283 inΔ +0.009 mm 5.7 mmmetric 0.2244 inΔ -0.091 mm 5.9 mmmetric 0.2323 inΔ +0.109 mm Aletter 0.2340 inΔ +0.152 mm 15/64fractional 0.2344 inΔ +0.162 mm

Same seriesNEAREST NOMINAL ROWS

#2number 5.613 mmΔ -0.178 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

#1drill bit size.

What sits beside #1.

ASME.

#1
drill bit size.