--- type: "drill-series" series: "number" name: "Number Drill Sizes" size_count: 60 smallest: "#60" largest: "#1" range_in: "0.0400–0.2280" range_mm: "1.016–5.791" standard: "ANSI/ASME B94.11M; BS 328" verified: "August 1, 2026" url: https://shopmath.org/drills/number --- # Number Drill Sizes — All 60 Sizes in Inches and Millimetres The number drill sizes series runs from #60 at 0.0400 in (1.016 mm) to #1 at 0.2280 in (5.791 mm), 60 sizes in all. Gauge-numbered twist drills, #1 (largest) through #80 (smallest). - **Series**: Number Drill Sizes - **Sizes**: 60 - **Smallest**: #60 — 0.0400 in - **Largest**: #1 — 0.2280 in - **Standard**: ANSI/ASME B94.11M; BS 328 ## Every Number Drill Size Each size links to its page with the nearest equivalent in the other three series and the threads it taps. | Drill | Diameter (in) | Diameter (mm) | Fraction | Taps | | --- | --- | --- | --- | --- | | [#1](https://shopmath.org/drills/number/1.md) | 0.2280 | 5.791 | | | | [#2](https://shopmath.org/drills/number/2.md) | 0.2210 | 5.613 | | | | [#3](https://shopmath.org/drills/number/3.md) | 0.2130 | 5.410 | | 1/4-28 UNF | | [#4](https://shopmath.org/drills/number/4.md) | 0.2090 | 5.309 | | | | [#5](https://shopmath.org/drills/number/5.md) | 0.2055 | 5.220 | | | | [#6](https://shopmath.org/drills/number/6.md) | 0.2040 | 5.182 | | | | [#7](https://shopmath.org/drills/number/7.md) | 0.2010 | 5.105 | | 1/4-20 UNC | | [#8](https://shopmath.org/drills/number/8.md) | 0.1990 | 5.055 | | | | [#9](https://shopmath.org/drills/number/9.md) | 0.1960 | 4.978 | | | | [#10](https://shopmath.org/drills/number/10.md) | 0.1935 | 4.915 | | | | [#11](https://shopmath.org/drills/number/11.md) | 0.1910 | 4.851 | | | | [#12](https://shopmath.org/drills/number/12.md) | 0.1890 | 4.801 | | | | [#13](https://shopmath.org/drills/number/13.md) | 0.1850 | 4.699 | | #12-32 UNEF | | [#14](https://shopmath.org/drills/number/14.md) | 0.1820 | 4.623 | | #12-28 UNF | | [#15](https://shopmath.org/drills/number/15.md) | 0.1800 | 4.572 | | | | [#16](https://shopmath.org/drills/number/16.md) | 0.1770 | 4.496 | | #12-24 UNC | | [#17](https://shopmath.org/drills/number/17.md) | 0.1730 | 4.394 | | | | [#18](https://shopmath.org/drills/number/18.md) | 0.1695 | 4.305 | | | | [#19](https://shopmath.org/drills/number/19.md) | 0.1660 | 4.216 | | | | [#20](https://shopmath.org/drills/number/20.md) | 0.1610 | 4.089 | | | | [#21](https://shopmath.org/drills/number/21.md) | 0.1590 | 4.039 | | #10-32 UNF | | [#22](https://shopmath.org/drills/number/22.md) | 0.1570 | 3.988 | | | | [#23](https://shopmath.org/drills/number/23.md) | 0.1540 | 3.912 | | | | [#24](https://shopmath.org/drills/number/24.md) | 0.1520 | 3.861 | | | | [#25](https://shopmath.org/drills/number/25.md) | 0.1495 | 3.797 | | #10-24 UNC | | [#26](https://shopmath.org/drills/number/26.md) | 0.1470 | 3.734 | | | | [#27](https://shopmath.org/drills/number/27.md) | 0.1440 | 3.658 | | | | [#28](https://shopmath.org/drills/number/28.md) | 0.1405 | 3.569 | | | | [#29](https://shopmath.org/drills/number/29.md) | 0.1360 | 3.454 | | #8-36 UNF, #8-32 UNC | | [#30](https://shopmath.org/drills/number/30.md) | 0.1285 | 3.264 | | | | [#31](https://shopmath.org/drills/number/31.md) | 0.1200 | 3.048 | | | | [#32](https://shopmath.org/drills/number/32.md) | 0.1160 | 2.946 | | | | [#33](https://shopmath.org/drills/number/33.md) | 0.1130 | 2.870 | | #6-40 UNF | | [#34](https://shopmath.org/drills/number/34.md) | 0.1110 | 2.819 | | | | [#35](https://shopmath.org/drills/number/35.md) | 0.1100 | 2.794 | | | | [#36](https://shopmath.org/drills/number/36.md) | 0.1065 | 2.705 | | #6-32 UNC | | [#37](https://shopmath.org/drills/number/37.md) | 0.1040 | 2.642 | | #5-44 UNF | | [#38](https://shopmath.org/drills/number/38.md) | 0.1015 | 2.578 | | #5-40 UNC | | [#39](https://shopmath.org/drills/number/39.md) | 0.0995 | 2.527 | | | | [#40](https://shopmath.org/drills/number/40.md) | 0.0980 | 2.489 | | | | [#41](https://shopmath.org/drills/number/41.md) | 0.0960 | 2.438 | | | | [#42](https://shopmath.org/drills/number/42.md) | 0.0935 | 2.375 | | #4-48 UNF | | [#43](https://shopmath.org/drills/number/43.md) | 0.0890 | 2.261 | | #4-40 UNC | | [#44](https://shopmath.org/drills/number/44.md) | 0.0860 | 2.184 | | | | [#45](https://shopmath.org/drills/number/45.md) | 0.0820 | 2.083 | | #3-56 UNF | | [#46](https://shopmath.org/drills/number/46.md) | 0.0810 | 2.057 | | | | [#47](https://shopmath.org/drills/number/47.md) | 0.0785 | 1.994 | | #3-48 UNC | | [#48](https://shopmath.org/drills/number/48.md) | 0.0760 | 1.930 | | | | [#49](https://shopmath.org/drills/number/49.md) | 0.0730 | 1.854 | | | | [#50](https://shopmath.org/drills/number/50.md) | 0.0700 | 1.778 | | #2-64 UNF, #2-56 UNC | | [#51](https://shopmath.org/drills/number/51.md) | 0.0670 | 1.702 | | | | [#52](https://shopmath.org/drills/number/52.md) | 0.0635 | 1.613 | | | | [#53](https://shopmath.org/drills/number/53.md) | 0.0595 | 1.511 | | #1-72 UNF, #1-64 UNC | | [#54](https://shopmath.org/drills/number/54.md) | 0.0550 | 1.397 | | | | [#55](https://shopmath.org/drills/number/55.md) | 0.0520 | 1.321 | | | | [#56](https://shopmath.org/drills/number/56.md) | 0.0465 | 1.181 | | | | [#57](https://shopmath.org/drills/number/57.md) | 0.0430 | 1.092 | | | | [#58](https://shopmath.org/drills/number/58.md) | 0.0420 | 1.067 | | | | [#59](https://shopmath.org/drills/number/59.md) | 0.0410 | 1.041 | | | | [#60](https://shopmath.org/drills/number/60.md) | 0.0400 | 1.016 | | | _Diameters are nominal. The taps column lists the threads this drill is the recommended tap drill for at the default engagement._ ## Sources and Method for the Number Drill Series ### Number drill sizes - **Source**: Number/letter: bd_warehouse drill_sizes.csv (Apache-2.0) cross-checked against Wikipedia Drill bit sizes (CC BY-SA 4.0). Fractional: computed 1/64 in steps per ANSI B94.11M. Metric: computed BS 328 increment pattern. - **Method**: compiled - **Verified against**: Wikipedia Drill bit sizes (CC BY-SA 4.0); 31/31 checks passed ### Assumptions - Drill diameters are nominal. A worn or run-out drill cuts oversize. - Dataset scope: Number sizes #61-#80 are stored but tagged demandTier 'extended' — query-space-map.md Appendix A found the tail thinning in the 60s. Sizes below #80 and metric sizes above 25.0 mm excluded. **Data last verified**: August 1, 2026 ## Related pages - All drill series: [Drill bit size reference](https://shopmath.org/drills.md) - Every series interleaved by diameter: [Drill size chart](https://shopmath.org/charts/drill-sizes.md) - Tap drills by thread: [Tap drill chart](https://shopmath.org/charts/tap-drill.md) --- *Source: [ShopMath](https://shopmath.org/drills/number) — data verified August 1, 2026. Reference data; verify against the governing standard before manufacture.*