攻牙底孔对照表如下：
公制螺纹攻牙底孔对照表
| 螺纹规格 | 底孔孔径（mm） | 螺纹规格 | 底孔孔径（mm） | 螺纹规格 | 底孔孔径（mm） | 螺纹规格 | 底孔孔径（mm） | 螺纹规格 | 底孔孔径（mm） | 螺纹规格 | 底孔孔径（mm） | 螺纹规格 | 底孔孔径（mm） | 螺纹规格 | 底孔孔径（mm） | 螺纹规格 | 底孔孔径（mm） | 螺纹规格 | 底孔孔径（mm） |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| M1×0.25 | 0.75 | M1.1×0.25 | 0.85 | M1.2×0.25 | 0.95 | M1.4×0.3 | 1.1 | M1.6×0.35 | 1.25 | M1.7×0.35 | 1.35 | M1.8×0.35 | 1.45 | M2.0×0.4 | 1.6 | M2.2×0.4 | 1.75 | M2.3×0.4 | 1.9 | M2.5×0.45 | 2.1 |
| M2.5×0.45 | 2.1 | M3×0.5 | 2.5 | M3.5×0.6 | 2.9 | M4×0.7 | 3.3 | M4.5×0.75 | 3.8 | M5×0.8 | 4.2 | M6×1 | 5 | M7×1 | 6 | M8×1.25 | 6.8 | M9×1.25 | 7.8 | M10×1.5 | 8.5 |
| M11×1.5 | 9.5 | M12×1.75 | 10.3 | M14×2 | 12 | M16×2 | 14 | M18×2.5 | 15.5 | M20×2.5 | 17.5 | M22×2.5 | 19.5 | M24×3 | 21 | M27×3 | 24 | M30×3.5 | 26.5 | M33×3.5 | 29.5 |
| M36×4 | 39 | M39×4 | 42 | M42×4.5 | 45 | M45×4.5 | 49 | M48×5 | 51 | | | | | | | | | |
英制螺纹攻牙底孔对照表
| 螺纹规格 | 底孔孔径（mm） | 螺纹规格 | 底孔孔径（mm） | 螺纹规格 | 底孔孔径（mm） | 螺纹规格 | 底孔孔径（mm） | 螺纹规格 | 底孔孔径（mm） | 螺纹规格 | 底孔孔径（mm） | 螺纹规格 | 底孔孔径（mm） | 螺纹规格 | 底孔孔径（mm） | 螺纹规格 | 底孔孔径（mm） |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| N0.25 | 0.75 | N0.3 | 0.85 | N0.4 | 0.95 | N0.6 | 1.1 | N0.7 | 1.25 | N0.8 | 1.4 | N1.0 | 1.5 | N1.2 | 1.6 | N1.4 | 1.75 | N1.6 | 1.9 |
| N1.7 | 1.35 | N1.8 | 1.45 | N2.0 | 1.6 | N2.2 | 1.75 | N2.3 | 1.