Metric Coarse Thread Bottom Hole Diameter
| Thread specification | Reference hole diameter | Minimum hole diameter | Maximum hole diameter (in MM) |
| M 1 × 0.25 | 0.75 | 0.729 | 0.785 |
| 1.1 × 0.25 | 0.85 | 0.829 | 0.885 |
| 1.2 × 0.25 | 0.95 | 0.929 | 0.985 |
| 1.4 × 0.3 | 1.1 | 1,075 | 1,142 |
| 1.6 × 0.35 | 1.25 | 1,221 | 1,321 |
| 1.8 × 0.35 | 1.45 | 1,421 | 1,521 |
| 2 × 0.4 | 1.6 | 1,567 | 1,679 |
| 2.2 × 0.45 | 1.75 | 1,713 | 1,838 |
| 2.5 × 0.45 | 2.1 | 2013 | 2,138 |
| 3 × 0.5 | 2.5 | 2,459 | 2,599 |
| 3.5 × 0.6 | 2.9 | 2.85 | 3.01 |
| 4 × 0.7 | 3.3 | 3,242 | 3,422 |
| 4.5 × 0.75 | 3.8 | 3,688 | 3,878 |
| 5 × 0.8 | 4.2 | 4,134 | 4,334 |
| 6×1 | 5 | 4,917 | 5,153 |
| 7×1 | 6 | 5,917 | 6,153 |
| 8×1.25 | 6.8 | 6,647 | 6,912 |
| 9×1.25 | 7.8 | 7,647 | 7,912 |
| 10×1.5 | 8.5 | 8,376 | 8,676 |
| 11×1.5 | 9.5 | 9,376 | 9,676 |
| 12×1.75 | 10.3 | 10,106 | 10,441 |
| 14×2 | 12 | 11,835 | 12/21 |
| 16×2 | 14 | 13,835 | 14.21 |
| 18×2.5 | 15.5 | 15,294 | 15,744 |
| 20×2.5 | 17.5 | 17,294 | 17,744 |
| 22×2.5 | 19.5 | 19,294 | 19,744 |
| 24×3 | 21 | 20,752 | 21,252 |
| 27×3 | 24 | 23,752 | 24,252 |
| 30×3.5 | 26.5 | 26,211 | 26,771 |
| 33×3.5 | 29.5 | 29,211 | 29,771 |
| 36×4 | 32 | 31.67 | 32.27 |
Imperial Thread Bottom Diameter Table
| Thread specification | Reference hole diameter | Minimum hole diameter | Maximum hole diameter (in MM) |
| NO.1 -64UNC | 1.55 | 1,425 | 1,582 |
| 2 -56 | 1.8 | 1,695 | 1,871 |
| 3 -48 | 2.1 | 1,941 | 2,146 |
| 4 -40 | 2.3 | 2,157 | 2,385 |
| 5 -40 | 2.6 | 2,487 | 2,697 |
| 6 -32 | 2.8 | 2,642 | 2,895 |
| 8 -32 | 3.4 | 3,302 | 3.53 |
| 10 -24 | 3.9 | 3,683 | 3,962 |
| 12 -24 | 4.5 | 4,344 | 4,597 |
| 1/4-20 tooth | 5.1 | 4,979 | 5,257 |
| 16/05 -18 | 6.6 | 6,401 | 6,731 |
| 3/8 -16 | 8 | 7,798 | 8,153 |
| 07/16 -14 | 9.4 | 9,144 | 9:55 am |
| 1/2 -13 | 10.8 | 10,592 | 11,023 |
| 16/09 -12 | 12.2 | 11,989 | 12,446 |
| 08/05 -11 | 13.6 | 13,386 | 13,868 |
| 3/4 -10 | 16.5 | 16,307 | 16.84 |
| 7/8 – 9 | 19.5 | 19,177 | 19,761 |
| 1 inch-8 | 22.2 | 21,971 | 22,606 |
Imperial Fine Thread Inner Hole Diameter Table
| Thread specification | Reference hole diameter | Minimum hole diameter | Maximum hole diameter (in MM) |
| 1 -72 | 1.55 | 1,474 | 1,612 |
| 2 -64 | 1.85 | 1,756 | 1,912 |
| 3 -56 | 2.1 | 2025 | 2,197 |
| 4 -48 | 2.4 | 2,271 | 2,458 |
| 5 -44 | 2.7 | 2,551 | 2.74 |
| 6 -40 | 2.9 | 2.82 | 3,022 |
| 8 -36 | 3.5 | 3,404 | 3,606 |
| 10 -32 | 4.1 | 3,963 | 4,165 |
| 12 -28 | 4.6 | 4,496 | 4,724 |
| 1/4–28 | 5.5 | 5.36 | 5,588 |
| 16/05 -24 | 6.9 | 6,782 | 7,035 |
| 3/8–24 teeth | 8.5 | 8,382 | 8,636 |
| 07/16 -20 | 9.9 | 9,729 | 10,033 |
| 1/2 -20 | 11.5 | 11,329 | 11,607 |
| 16/09 -18 | 12.9 | 12,751 | 13,081 |
| 08/05 -18 | 14.5 | 14,351 | 14,681 |
| 3/4 -16 | 17.5 | 17,323 | 17,678 |
| 07/08–14 | 20.5 | 8:27 p.m. | 20,675 |
| 1 inch-12 | 23.2 | 23,114 | 23,571 |
Metric fine thread bottom diameter chart and other thread pitches
| Thread specification | Reference hole diameter | Minimum hole diameter | Maximum hole diameter (in MM) |
| M 2.5 × 0.35 | 2.2 | 2,121 | 2,221 |
| 3 × 0.35 | 2.7 | 2,621 | 2,721 |
| 3.5 × 0.35 | 3.2 | 3,121 | 3,221 |
| 4 × 0.5 | 3.5 | 3,459 | 3,599 |
| 4.5 × 0.5 | 4 | 3,959 | 4,099 |
| 5 × 0.5 | 4.5 | 4,459 | 4,599 |
| 5.5 × 0.5 | 5 | 4,959 | 5,099 |
| 6 × 0.75 | 5.3 | 5,188 | 5,378 |
| 7 × 0.75 | 6.3 | 6,188 | 6,378 |
| 8×1 | 7 | 6,917 | 7,153 |
| 8 × 0.75 | 7.3 | 7,188 | 7,378 |
| 9×1 | 8 | 7,917 | 8,153 |
| 9 × 0.75 | 8.3 | 8,188 | 8,378 |
| 10×1.25 | 8.8 | 8,647 | 8,912 |
| 10×1 | 9 | 8,917 | 9,153 |
| 10 × 0.75 | 9.3 | 9,188 | 9,378 |
| 11×1 | 10 | 9,917 | 10,153 |
| 11 × 0.75 | 10.3 | 10,188 | 10,378 |
| 12×1.5 | 10.5 | 10,376 | 10,676 |
| 12×1.25 | 10.8 | 10,647 | 10,912 |
| 12×1 | 11 | 10,917 | 11,153 |
| 14×1.5 | 12.5 | 12,376 | 12,676 |
| 14×1 | 13 | 12,917 | 13,153 |
| 15×1.5 | 13.5 | 13,376 | 13,676 |
| 15×1 | 14 | 13,917 | 14,153 |
| 16×1.5 | 14.5 | 14,376 | 14,676 |
| 16×1 | 15 | 14,917 | 15,153 |
Metric External Thread Outer Diameter Chart
Just like the internal diameter of the thread, the external diameter also has its standards. Some users may unnecessarily mark the tolerance on the thread outer diameter (except those with specific usage requirements for the outer diameter). Below is the outer diameter table for coarse metric thread, in MM.
Metric 60° Coarse Thread Standard External Diameter Table:
| Specifications | Tone | External thread diameter | Thread rolling diameter | |
| Max. | Minimum | ±0.02 | ||
| M1.4 | 0.3 | 1.38 | 1.34 | 1.16 |
| M1.7 | 0.35 | 1.68 | 1.61 | 1.42 |
| M2.0 | 0.4 | 1.98 | 1.89 | 1.68 |
| M2.3 | 0.4 | 2.28 | 2.19 | 1.98 |
| M2.5 | 0.45 | 2.48 | 2.38 | 2.15 |
| M3.0 | 0.5 | 2.98 | 2.88 | 2.6 |
| M3.5 | 0.6 | 3.47 | 3.36 | 3.02 |
| M4.0 | 0.7 | 3.98 | 3.83 | 3.4 |
| M4.5 | 0.75 | 4.47 | 4.36 | 3.88 |
| M5.0 | 0.8 | 4.98 | 4.83 | 4.3 |
| M6.0 | 1 | 5.97 | 5.82 | 5.18 |
| M7.0 | 1 | 6.97 | 6.82 | 6.18 |
| M8.0 | 1.25 | 7.96 | 7.79 | 7.02 |
| M9.0 | 1.25 | 8.96 | 8.79 | 8.01 |
| M10 | 1.5 | 9.96 | 9.77 | 8.84 |
| M11 | 1.5 | 10.97 | 10.73 | 9.84 |
| M12 | 1.75 | 11:95 am | 11.76 | 10.7 |
| M14 | 1.75 | 13.95 | 13.74 | 12.5 |
| M16 | two | 15.95 | 15.74 | 14.5 |
| M18 | two | 5:95 p.m. | 17.71 | 16.2 |
| M20 | 2.5 | 7:95 p.m. | 19.71 | 18.2 |
This standard references GB9145-88; Please note that it is a “reference”, not equivalent to the GB9145. The standards listed in this table are slightly higher than GB9145.”
