本表所推选钻头孔径，是针对攻牙加工时，能够很容易的了解钻头直径，而依据市售的标准钻头所选定的，在使用钻头的情况下，由于钻头的形状及尺寸，精度，被钻孔的材质等，对于所钻孔的尺寸，精度有很大影响，所以使用本表的钻孔径，若有不当之处，应实际状况适当的变更钻头直径，本表依据2级牙制订。
| 公制粗螺纹 | |||
| 规格 | 标准径 | 2级牙钻孔径 | |
| 最大 | 最小 | ||
| M1.0×0.25 | 0.75 | 0.785 | 0.729 |
| M1.1×0.25 | 0.85 | 0.885 | 0.829 |
| M1.2×0.25 | 0.95 | 0.985 | 0.929 |
| M1.4×0.3 | 1.10 | 1.142 | 1.075 |
| M1.6×0.35 | 1.25 | 1.321 | 1.221 |
| M1.7×0.35 | 1.35 | 1.421 | 1.321 |
| M1.8×0.35 | 1.45 | 1.521 | 1.421 |
| M2.0×0.4 | 1.60 | 1.679 | 1.567 |
| M2.2×0.45 | 1.75 | 1.838 | 1.713 |
| M2.3×0.4 | 1.90 | 1.979 | 1.867 |
| M2.5×0.45 | 2.10 | 2.138 | 2.013 |
| M2.6×0.45 | 2.20 | 2.238 | 2.113 |
| M3.0×0.5 | 2.50 | 2.599 | 2.459 |
| M3.0×0.6 | 2.40 | 2.44 | 2.280 |
| M3.5×0.6 | 2.90 | 3.010 | 2.850 |
| M4.0×0.7 | 3.30 | 3.422 | 3.242 |
| M4.0×0.75 | 3.25 | 3.326 | 3.106 |
| M4.5×0.75 | 3.80 | 3.878 | 3.688 |
| M5.0×0.8 | 4.20 | 4.334 | 4.134 |
| M5.0×0.9 | 4.10 | 4.170 | 3.930 |
| M6.0×1.0 | 5.00 | 5.153 | 4.917 |
| M7.0×1.0 | 6.00 | 6.153 | 5.917 |
| M8.0×1.25 | 6.80 | 6.912 | 6.647 |
| M9.0×1.25 | 7.80 | 7.912 | 7.647 |
| M10×1.5 | 8.50 | 8.676 | 8.376 |
| M11×1.5 | 9.50 | 9.676 | 9.376 |
| M12×1.75 | 10.30 | 10.441 | 10.106 |
| M14×2.0 | 12.00 | 12.210 | 11.735 |
| M16×2.0 | 14.00 | 14.210 | 13.835 |
| M18×2.5 | 15.50 | 15.744 | 15.294 |
| M20×2.5 | 17.50 | 17.744 | 17.294 |
| M22×2.5 | 19.50 | 19.744 | 19.294 |
| M24×3.0 | 21.00 | 21.252 | 2.752 |
| M27×3.0 | 24.00 | 24.252 | 23.752 |
| M30×3.5 | 26.50 | 26.771 | 26.211 |
| 公制细螺纹 | |||
| 规格 | 标准径 | 2级牙钻孔径 | |
| 最大 | 最小 | ||
| M1.0×0.2 | 0.80 | 0.821 | 0.783 |
| M1.1×0.2 | 0.90 | 0.921 | 0.883 |
| M1.2×0.2 | 1.00 | 1.021 | 0.983 |
| M1.4×0.2 | 1.20 | 1.221 | 0.183 |
| M1.6×0.2 | 1.40 | 1.421 | 1.383 |
| M1.7×0.2 | 1.45 | 1.500 | 1.460 |
| M1.8×0.2 | 1.60 | 1.621 | 1.583 |
| M2.0×0.25 | 1.75 | 1.785 | 1.729 |
| M2.2×0.25 | 1.95 | 1.985 | 1.929 |
| M2.3×0.25 | 2.05 | 2.061 | 2.001 |
| M2.5×0.35 | 2.20 | 2.221 | 2.121 |
| M2.6×0.35 | 2.20 | 2.246 | 2.186 |
| M3.0×0.35 | 2.70 | 2.721 | 2.621 |
| M3.5×0.35 | 3.20 | 3.221 | 3.121 |
| M4.0×0.5 | 3.50 | 3.599 | 3.459 |
| M4.5×0.5 | 4.00 | 4.099 | 3.959 |
| M5×0.5 | 4.50 | 4.599 | 4.459 |
| M5.5×0.5 | 5.00 | 5.099 | 4.959 |
| M6.0×0.75 | 5.30 | 5.378 | 5.188 |
| M6.0×0.5 | 5.50 | 5.550 | 5.400 |
| M7.0×0.75 | 6.30 | 6.378 | 61.88 |
| M7.0×0.5 | 6.50 | 6.550 | 64.00 |
| M8.0×1.0 | 7.00 | 7.153 | 6.917 |
| M8.0×0.75 | 7.30 | 7.378 | 7.188 |
| M8×0.5 | 7.50 | 7.520 | 7.400 |
| M9×1.0 | 8.00 | 8.153 | 7.917 |
| M9×0.75 | 8.30 | 8.378 | 8.188 |
| M10×1.25 | 8.80 | 8.912 | 8.647 |
| M10×1.0 | 9.00 | 9.153 | 8.917 |
| M10×0.75 | 9.30 | 9.378 | 9.188 |
| M10×0.5 | 9.50 | 9.520 | 9.400 |
| M11×1.0 | 10.00 | 10.153 | 9.917 |
| M11×0.75 | 10.30 | 10.378 | 10.188 |
| M11×1.5 | 10.50 | 10.676 | 10.376 |
| M12×1.25 | 10.80 | 10.912 | 10.647 |
| 公制细螺纹 | |||
| 规格 | 标准径 | 2级牙钻孔径 | |
| 最大 | 最小 | ||
| M12×1.0 | 11.00 | 11.153 | 10.917 |
| M12×0.5 | 11.50 | 11.520 | 11.4 |
| M14×1.5 | 12.50 | 12.676 | 12.376 |
| M14×1.0 | 13.00 | 13.153 | 12.917 |
| M15×1.5 | 13.50 | 13.676 | 13.376 |
| M15×1.0 | 14.00 | 14.153 | 13.917 |
| M16×1.5 | 14.50 | 14.676 | 14.376 |
| M16×1.0 | 15.00 | 15.153 | 14.917 |
| M17×1.5 | 15.50 | 15.676 | 15.376 |
| M17×1.0 | 16.00 | 16.153 | 15.917 |
| M18×2.0 | 16.00 | 16.210 | 15.835 |
| M18×1.5 | 16.50 | 16.670 | 16.376 |
| M18×1.0 | 17.00 | 17.153 | 16.917 |
| M20×2.0 | 18.00 | 18.210 | 17.835 |
| M20×1.5 | 18.50 | 18.676 | 18.376 |
| M20×1.0 | 19.00 | 19.153 | 18.917 |
| M20×2.0 | 20.00 | 20.210 | 19.835 |
| M22×1.5 | 20.50 | 20.676 | 20.376 |
| M22×1.0 | 21.00 | 21.153 | 20.917 |
| M24×2.0 | 22.00 | 22.210 | 21.835 |
| M24×1.5 | 22.50 | 22.676 | 22.376 |
| M24×1.0 | 23.00 | 23.153 | 22.917 |
| M25×2.0 | 23.00 | 23.210 | 22.835 |
| M25×1.5 | 23.50 | 23.676 | 23.376 |
| M25×1.0 | 24.00 | 24.153 | 23.917 |
| M26×1.5 | 24.50 | 24.676 | 24.376 |
| M27×2.0 | 25.00 | 25.210 | 24.835 |
| M27×1.5 | 25.50 | 25.676 | 25.376 |
| M27×1.0 | 26.00 | 26.153 | 25.917 |
| M28×2.0 | 26.00 | 26.210 | 25.835 |
| M28×1.5 | 26.50 | 26.676 | 26.376 |
| M28×1.0 | 27.00 | 27.153 | 26.917 |
| M30×3.0 | 27.00 | 27.252 | 26.752 |
| M30×2.0 | 28.00 | 28.210 | 27.835 |
| M30×1.5 | 28.50 | 28.676 | 28.376 |
| M30×1.0 | 29.00 | 29.153 | 28.917 |
| M32×2.0 | 30.00 | 30.210 | 29.835 |
| M32×1.5 | 30.50 | 30.676 | 30.376 |
| M33×3.0 | 30.00 | 30.252 | 29.752 |
| M33×2.0 | 31.00 | 31.210 | 30.835 |
| M33×1.5 | 31.50 | 31.376 | 31.376 |
| M35×1.5 | 33.50 | 33.676 | 33.376 |
| M36×3.0 | 33.00 | 33.252 | 32.752 |
| M36×2.0 | 34.00 | 34.210 | 33.835 |
| M36×1.5 | 34.50 | 34.676 | 34.376 |
| 美制细螺纹 | |||
| 规格(UNF) | 标准径 | 2级牙钻孔径 | |
| 最大 | 最小 | ||
| 番数牙外径 | |||
| NO.0-80(1.524) | 1.25 | 1.305 | 1.182 |
| NO.1-72(1.854) | 1.55 | 1.612 | 1.474 |
| NO.2-64(2.184) | 1.85 | 1.912 | 1.756 |
| NO.3-56(2.515) | 2.10 | 2.197 | 2.025 |
| NO.4-48(2.845) | 2.40 | 2.458 | 2.271 |
| NO.5-44(3.175) | 2.70 | 2.740 | 2.551 |
| NO.6-40(3.505) | 2.90 | 3.022 | 2.820 |
| NO.8-36(4.166) | 3.50 | 3.606 | 3.404 |
| NO.10-32(4.826) | 4.10 | 4.165 | 3.963 |
| NO.12-28(5.846) | 4.60 | 4.724 | 4.496 |
| 1/4 -28 | 5.50 | 5.588 | 5.360 |
| 5/16 -24 | 6.90 | 7.035 | 6.782 |
| 3/8 -24 | 8.50 | 8.636 | 8.382 |
| 7/16 -20 | 9.90 | 10.033 | 9.729 |
| 1/2 -20 | 11.50 | 11.607 | 11.329 |
| 9/16 -18 | 12.90 | 13.081 | 12.751 |
| 5/8 -18 | 14.50 | 14.681 | 14.351 |
| 3/4 -16 | 17.50 | 14.678 | 17.323 |
| 7/8 -14 | 20.50 | 20.675 | 20.270 |
| 1 -12 | 23.20 | 23.571 | 23.114 |
| 1-1/8 -12 | 26.50 | 26.746 | 26.289 |
| 1-1/4 -12 | 29.50 | 29.921 | 29.464 |
| 1-3/8 -12 | 32.80 | 33.096 | 32.464 |
| 1-1/2 -12 | 36.00 | 36.270 | 35.814 |
| 无屑丝攻钻孔径 | ||||
| 规格 | 精度等级 | |||
| RH4.5.6 | RH7.8 | RH9 | ||
| M1.0×0.25 | 0.86 | 0.88 | – | |
| M1.1×0.25 | 0.96 | 0.98 | – | |
| M1.2×0.25 | 1.06 | 1.08 | – | |
| M1.4×0.3 | 1.24 | 1.25 | – | |
| M1.6×0.35 | 1.41 | 1.43 | – | |
| M1.7×0.35 | 1.51 | 1.53 | – | |
| M1.8×0.35 | 1.61 | 1.63 | – | |
| M2.0×0.4 | 1.78 | 1.80 | – | |
| M2.2×0.45 | 1.95 | 1.98 | – | |
| M2.3×0.4 | 2.08 | 2.10 | – | |
| M2.5×0.45 | 2.25 | 2.28 | – | |
| M2.6×0.45 | 2.35 | 1.38 | – | |
| M3.0×0.5 | 2.73 | 2.75 | – | |
| M3.0×0.6 | 3.17 | 3.20 | – | |
| M4.0×0.7 | 3.62 | 3.65 | 3.69 | |
| M5.0×0.8 | 4.56 | 4.60 | 4.64 | |
| M6.0×1.0 | 5.45 | 5.50 | 5.55 | |
| M7.0×1.0 | 6.45 | 6.50 | 6.55 | |
| M8.0×1.25 | 7.31 | 7.38 | 7.44 | |
| M10×1.5 | 9.18 | 9.25 | 9.32 | |
| M10×1.25 | 9.31 | 9.38 | 9.44 | |
| M12×1.75 | 11.04 | 11.12 | 11.21 | |
| M12×1.25 | 11.31 | 11.38 | 11.44 | |
| 注：无槽丝攻之钻孔径,在上表所列之数值,由于被加工材料之材质、硬度、形状、尺寸等之影响,多少会有所变动，因此参考上表之同时,亦请增减若干。 | ||||
| 美制管螺纹 | |||
| 规格(UNEF) | 标准径 | 2级牙钻孔径 | |
| 最大 | 最小 | ||
| NO.12 -32 | 4.70 | 4.826 | 4.623 |
| 1/4 -32 | 5.60 | 5.690 | 5.486 |
| 5/16 -32 | 7.10 | 7.264 | 7.087 |
| 3/8 -32 | 8.70 | 8.865 | 8.661 |
| 7/16 -28 | 10.20 | 10.338 | 10.135 |
| 1/2 -28 | 11.80 | 11.938 | 11.709 |
| 9/16 -28 | 13.20 | 13.386 | 13.132 |
| 5/8 -24 | 14.80 | 14.986 | 14.732 |
| 3/4 -20 | 17.80 | 17.958 | 17.678 |
| 7/8 -20 | 21.00 | 21.133 | 20.853 |
| 1 -20 | 24.00 | 24.308 | 24.028 |
| 美制粗螺纹 | |||
| 规格(UNC) | 标准径 | 2级牙钻孔径 | |
| 番数牙外径 | 最大 | 最小 | |
| NO.1-64(1.854) | 1.55 | 1.582 | 1.425 |
| NO.2-56(2.184) | 1.80 | 1.871 | 1.695 |
| NO.3-48(2.515) | 2.10 | 2.146 | 1.941 |
| NO.4-40(2.845) | 2.30 | 2.385 | 2.157 |
| NO.5-40(3.175) | 2.60 | 2.697 | 2.487 |
| NO.6-32(3.505) | 2.80 | 2.895 | 2.642 |
| NO.8-32(4.166) | 3.40 | 3.530 | 3.302 |
| NO.10-24(4.826) | 3.90 | 3.962 | 3.682 |
| NO.12-24(5.846) | 4.50 | 4.597 | 4.344 |
| 1/4 -20 | 5.10 | 5.257 | 4.979 |
| 5/16 -18 | 6.60 | 6.731 | 6.401 |
| 3/8 -16 | 8.00 | 8.153 | 7.987 |
| 7/16 -14 | 9.40 | 9.500 | 9.144 |
| 1/2 -13 | 10.80 | 11.023 | 10.592 |
| 9/16 -12 | 12.20 | 12.446 | 11.989 |
| 5/8 -11 | 13.60 | 12.868 | 13.386 |
| 3/4 -10 | 16.20 | 16.840 | 16.307 |
| 7/8 -9 | 19.50 | 19.761 | 19.177 |
| 1 -8 | 22.20 | 22.606 | 21.971 |
| 1-1/8 -7 | 25.00 | 25.349 | 24.638 |
| 1-1/4 -7 | 28.20 | 28.524 | 27.813 |
| 1-3/8 -6 | 30.80 | 31.115 | 30.353 |
| 1-1/2 -6 | 34.00 | 34.290 | 33.528 |
| 1-3/4 -5 | 39.50 | 39.827 | 38.964 |
| 2 -4-1/2 | 45.20 | 45.593 | 44.679 |
| 英制螺纹 | ||
| 规格 | 钻孔径 | |
| 硬材 | 软材 | |
| W1/8 – 40 | 2.65 | 2.60 |
| W5/32 – 32 | 3.25 | 3.20 |
| W3/16 – 24 | 3.75 | 3.70 |
| W1/4 – 20 | 5.10 | 5.00 |
| W5/16 – 18 | 6.60 | 6.50 |
| W3/8 – 16 | 8.00 | 7.90 |
| W7/16 – 14 | 9.40 | 9.30 |
| W1/2 – 12 | 10.70 | 10.50 |
| W9/16 – 12 | 12.30 | 12.00 |
| W5/8 – 11 | 13.70 | 13.50 |
| W3/4 – 10 | 16.70 | 16.50 |
| W7/8 – 9 | 19.50 | 19.30 |
| W1 – 8 | 22.40 | 22.00 |
| W1-1/8 – 7 | 25.00 | 24.80 |
| W1-1/4 – 7 | 28.30 | 28.00 |
| 英制管螺纹 | |||
| 规格 | 标准径 | 钻孔径 | |
| 最大 | 最小 | ||
| PS1/16 -28 | 6.50 | 6.632 | 6.490 |
| PS1/8 -28 | 8.50 | 8.637 | 8.495 |
| PS1/4 – 19 | 11.40 | 11.549 | 11.341 |
| PS3/8 – 19 | 15.00 | 15.054 | 14.846 |
| PS1/2 – 14 | 18.50 | 18.773 | 18.489 |
| PS3/4 – 14 | 24.00 | 24.259 | 23.975 |
| PS1 – 11 | 30.20 | 30.471 | 30.111 |
| PS1-1/4 -11 | 38.80 | 39.132 | 38.772 |
| PS1-1/2 -11 | 44.80 | 45.025 | 44.665 |
| PS2 – 11 | 56.50 | 56.836 | 56.476 |
| 英制管螺纹 | ||||
| 规格 | 标准径 | 有效牙部之长度(最小)中之母螺牙内径 | 标准长度(最小)中之母螺牙内径 | |
| 使用绞刀时 | 不用绞刀时 | |||
| PT1/16 -28 | 6.10 | 6.2 | 6.244 | 6.384 |
| PT1/8 -28 | 8.10 | 8.2 | 8.249 | 8.388 |
| PT1/4 -19 | 10.70 | 11 | 10.962 | 11.174 |
| PT3/8 -19 | 14.20 | 14.5 | 14.448 | 14.658 |
| PT1/2 -14 | 17.60 | 18 | 17.979 | 18.263 |
| PT3/4 -14 | 23.00 | 23.5 | 23.378 | 23.663 |
| Pt1 -11 | 29.00 | 29.5 | 29.459 | 29.822 |
| PT1-1/4 -11 | 37.50 | 38 | 37.976 | 38.339 |
| PT1-1/2 -11 | 43.40 | 44 | 43.869 | 44.232 |
| Pt2 -11 | 54.90 | 55.5 | 55.412 | 55.844 |
| 美制螺纹滚造径 | |||
| 规格 | 钻孔径 | ||
| NPT | NPS | ||
| 使用绞刀时 | 不用绞刀时 | ||
| 1/16 -27 | 6.1 | 6.25 | 6.35 |
| 1/8 -27 | 8.33 | 8.43 | 8.74 |
| 1/4 -18 | 10.72 | 11.13 | 11.13 |
| 3/8 -18 | 14.27 | 14.27 | 14.68 |
| 1/2 -14 | 17.48 | 17.86 | 18.26 |
| 3/4 -14 | 22.63 | 23.01 | 23.42 |
| 1 -11-1/2 | 28.58 | 28.98 | 29.36 |
| 1-1/4-11-1/2 | 37.31 | 37.69 | 38.1 |
| 1-1/2-11-1/2 | 43.66 | 44.04 | 44.45 |
| 2 -11-1/2 | 55.58 | 55.96 | 56.36 |
| 英制螺纹滚造径 | |
| 规格 | 滚造径 |
| W 3/16 – 24 | 4.08 – 4.05 |
| W 1/4 – 20 | 5.51 – 5.46 |
| W 5/16 – 18 | 7.01 – 6.95 |
| W 3/8 – 16 | 8.48 – 8.41 |
| W 7/16 – 14 | 9.92 – 9.85 |
| W 1/2 – 12 | 11.31 – 11.24 |
| W 9/16 -12 | 12.89 – 12.82 |
| 公制螺纹 | ||
| 规格 | 滚造径 | |
| M3.0×0.5 | 2.63 2.60 | |
| M3.0×0.6 | 2.56 2.53 | |
| M3.5×0.6 | 3.06 3.03 | |
| M4.0×0.7 | 3.49 3.45 | |
| M4.0×0.75 | 3.45 3.41 | |
| M4.5×0.75 | 3.96 3.92 | |
| M5.0×0.8 | 4.43 4.38 | |
| M5.0×0.9 | 4.36 4.31 | |
| M6.0×1.0 | 5.30 5.25 | |
| M7.0×1.0 | 6.30 6.25 | |
| M8.0×1.0 | 7.28 – 7.23 | |
| M8.0×1.25 | 7.12 – 7.07 | |
| M9.0×1.25 | 8.12 – 8.07 | |
| M10×1.25 | 9.10 – 9.04 | |
| M10×1.5 | 8.97 – 8.91 | |
| M11×1.5 | 9.97 – 9.91 | |
| M12×1.5 | 10.92 – 10.87 | |
| M12×1.75 | 10.79 – 10.73 | |
| M14×2.0 | 12.63 – 12.56 | |
| M16×2.0 | 14.63 – 14.56 | |
| M18×2.5 | 16.31 – 16.23 | |
| M20×2.5 | 18.31 – 18.23 | |
| M22×2.5 | 20.31 – 20.23 | |
| 针车用螺纹 | |
| 规格(UNC) | 滚造径 |
| SM 1/8 40 | 2.735 -2.688 |
| SM 1/8 44 | 2.769 -2.722 |
| SM 9/64 40 | 3.128 -3.083 |
| SM 11/64 40 | 3.855 -3.805 |
| SM 3/16 32 | 4.205 -4.155 |
| SM 3/16 28 | 4.143 -4.093 |
| SM 7/32 32 | 5.003 -4.955 |
| SM 15/64 28 | 5.325 -4.955 |
| SM 1/4 40 | 5.890 -5.735 |
| SM 1/4 28 | 5.721 -5.366 |
| SM 9/32 28 | 6.528 -6.648 |
| SM 11/32 28 | 8.092 -8.432 |
| SM 3/8 29 | 8.880 -8.015 |
| SM 7/16 30 | 10.466 -10.401 |
| SM 7/16 16 | 10.037 -9.967 |
| SM 1/2 20 | 11.819 -11.749 |
| SM 9/16 20 | 13.400 -13.425 |
| 美制粗螺纹 | |
| 规格(UNC) | 滚造径 |
| NO.5-40 | 2.70 – 2.67 |
| NO.6-32 | 2.95 – 2.91 |
| NO.8-32 | 3.60 – 3.57 |
| NO.10-24 | 4.09 – 4.05 |
| NO.12-24 | 4.75 – 4.70 |
| 1/4 -20 | 5.50 – 5.45 |
| 5/16 -18 | 6.98 – 6.93 |
| 3/8 -16 | 8.45 – 8.40 |
| 7/16 -14 | 9.89 – 9.83 |
| 1/2 -13 | 11.39 – 11.32 |
| 9/16 -12 | 12.87 – 12.80 |
| 美制细螺纹 | |
| 规格(UNF) | 滚造径 |
| NO.5-44 | 2.73 – 2.70 |
| NO.6-40 | 3.05 – 3.02 |
| NO.8-36 | 3.66 – 3.63 |
| NO.10-32 | 4.26 – 4.80 |
| NO.12-28 | 4.84 – 4.80 |
| 1/4 -28 | 5.72 – 5.68 |
| 5/16 -24 | 7.20 – 7.16 |
| 3/8 -24 | 8.79 – 8.74 |
| 7/16 -20 | 10.23 – 10.18 |
| 1/2 -20 | 11.82 – 11.76 |