Metric fine threads: dimensions and tap drill
Full chart with the tap drill for every size. Press “Calculate” on any row to open the calculator with that thread.
A fine pitch is always stated on the drawing (“M12 x 1.25”). For the same diameter it leaves a thicker core and more threads per length: it resists vibration better, allows fine adjustment and is common in thin walls, bearing lock nuts and aerospace. In exchange, it is damaged more easily and needs a more accurate tap drill.
Choose the diameter and pitch from the table, then calculate the tap drill or prepare the threading cycle.
| Thread | Pitch (mm) | Major Ø (mm) | Drill for cutting tap | Drill for forming tap | Nut minor Ø (mm) | Calculate |
|---|---|---|---|---|---|---|
| M3 x 0.35 | 0.35 | 3 | ⌀ 2.65 | ⌀ 2.85 | 2.621 | |
| M4 x 0.5 | 0.5 | 4 | ⌀ 3.5 | ⌀ 3.8 | 3.459 | |
| M5 x 0.5 | 0.5 | 5 | ⌀ 4.5 | ⌀ 4.8 | 4.459 | |
| M6 x 0.75 | 0.75 | 6 | ⌀ 5.2 | ⌀ 5.6 | 5.188 | |
| M8 x 0.75 | 0.75 | 8 | ⌀ 7.2 | ⌀ 7.6 | 7.188 | |
| M8 x 1 | 1 | 8 | ⌀ 7 | ⌀ 7.5 | 6.917 | |
| M10 x 0.75 | 0.75 | 10 | ⌀ 9.2 | ⌀ 9.6 | 9.188 | |
| M10 x 1 | 1 | 10 | ⌀ 9 | ⌀ 9.5 | 8.917 | |
| M10 x 1.25 | 1.25 | 10 | ⌀ 8.8 | ⌀ 9.4 | 8.647 | |
| M12 x 1 | 1 | 12 | ⌀ 11 | ⌀ 11.5 | 10.917 | |
| M12 x 1.25 | 1.25 | 12 | ⌀ 10.8 | ⌀ 11.4 | 10.647 | |
| M12 x 1.5 | 1.5 | 12 | ⌀ 10.5 | ⌀ 11.3 | 10.376 | |
| M14 x 1 | 1 | 14 | ⌀ 13 | ⌀ 13.5 | 12.917 | |
| M14 x 1.25 | 1.25 | 14 | ⌀ 12.8 | ⌀ 13.5 | 12.647 | |
| M14 x 1.5 | 1.5 | 14 | ⌀ 12.5 | ⌀ 13.5 | 12.376 | |
| M16 x 1 | 1 | 16 | ⌀ 15 | ⌀ 15.5 | 14.917 | |
| M16 x 1.5 | 1.5 | 16 | ⌀ 14.5 | ⌀ 15.5 | 14.376 | |
| M18 x 1 | 1 | 18 | ⌀ 17 | ⌀ 17.5 | 16.917 | |
| M18 x 1.5 | 1.5 | 18 | ⌀ 16.5 | ⌀ 17.5 | 16.376 | |
| M18 x 2 | 2 | 18 | ⌀ 16 | ⌀ 17 | 15.835 | |
| M20 x 1 | 1 | 20 | ⌀ 19 | ⌀ 19.5 | 18.917 | |
| M20 x 1.5 | 1.5 | 20 | ⌀ 18.5 | ⌀ 19.5 | 18.376 | |
| M20 x 2 | 2 | 20 | ⌀ 18 | ⌀ 19 | 17.835 | |
| M22 x 1 | 1 | 22 | ⌀ 21 | ⌀ 21.5 | 20.917 | |
| M22 x 1.5 | 1.5 | 22 | ⌀ 20.5 | ⌀ 21.5 | 20.376 | |
| M22 x 2 | 2 | 22 | ⌀ 20 | ⌀ 21 | 19.835 | |
| M24 x 1.5 | 1.5 | 24 | ⌀ 22.5 | ⌀ 23.5 | 22.376 | |
| M24 x 2 | 2 | 24 | ⌀ 22 | ⌀ 23 | 21.835 | |
| M27 x 1.5 | 1.5 | 27 | ⌀ 25.5 | ⌀ 26.5 | 25.376 | |
| M27 x 2 | 2 | 27 | ⌀ 25 | ⌀ 26 | 24.835 | |
| M30 x 1.5 | 1.5 | 30 | ⌀ 28.5 | ⌀ 29.5 | 28.376 | |
| M30 x 2 | 2 | 30 | ⌀ 28 | ⌀ 29 | 27.835 | |
| M30 x 3 | 3 | 30 | ⌀ 27 | ⌀ 28.5 | 26.752 | |
| M33 x 1.5 | 1.5 | 33 | ⌀ 31.5 | ⌀ 32.5 | 31.376 | |
| M33 x 2 | 2 | 33 | ⌀ 31 | ⌀ 32 | 30.835 | |
| M33 x 3 | 3 | 33 | ⌀ 30 | ⌀ 31.5 | 29.752 | |
| M36 x 1.5 | 1.5 | 36 | ⌀ 34.5 | ⌀ 35.5 | 34.376 | |
| M36 x 2 | 2 | 36 | ⌀ 34 | ⌀ 35 | 33.835 | |
| M36 x 3 | 3 | 36 | ⌀ 33 | ⌀ 34.5 | 32.752 | |
| M39 x 1.5 | 1.5 | 39 | ⌀ 37.5 | ⌀ 38.5 | 37.376 | |
| M39 x 2 | 2 | 39 | ⌀ 37 | ⌀ 38 | 36.835 | |
| M39 x 3 | 3 | 39 | ⌀ 36 | ⌀ 37.5 | 35.752 | |
| M42 x 1.5 | 1.5 | 42 | ⌀ 40.5 | ⌀ 41.5 | 40.376 | |
| M42 x 2 | 2 | 42 | ⌀ 40 | ⌀ 41 | 39.835 | |
| M42 x 3 | 3 | 42 | ⌀ 39 | ⌀ 40.5 | 38.752 | |
| M45 x 1.5 | 1.5 | 45 | ⌀ 43.5 | ⌀ 44.5 | 43.376 | |
| M45 x 2 | 2 | 45 | ⌀ 43 | ⌀ 44 | 42.835 | |
| M45 x 3 | 3 | 45 | ⌀ 42 | ⌀ 43.5 | 41.752 | |
| M48 x 1.5 | 1.5 | 48 | ⌀ 46.5 | ⌀ 47.5 | 46.376 | |
| M48 x 2 | 2 | 48 | ⌀ 46 | ⌀ 47 | 45.835 | |
| M48 x 3 | 3 | 48 | ⌀ 45 | ⌀ 46.5 | 44.752 | |
| M52 x 1.5 | 1.5 | 52 | ⌀ 50.5 | ⌀ 51.5 | 50.376 | |
| M52 x 2 | 2 | 52 | ⌀ 50 | ⌀ 51 | 49.835 | |
| M52 x 3 | 3 | 52 | ⌀ 49 | ⌀ 50.5 | 48.752 | |
| M52 x 4 | 4 | 52 | ⌀ 48 | ⌀ 50 | 47.67 | |
| M56 x 2 | 2 | 56 | ⌀ 54 | ⌀ 55 | 53.835 | |
| M56 x 3 | 3 | 56 | ⌀ 53 | ⌀ 54.5 | 52.752 | |
| M56 x 4 | 4 | 56 | ⌀ 52 | ⌀ 54 | 51.67 | |
| M60 x 2 | 2 | 60 | ⌀ 58 | ⌀ 59 | 57.835 | |
| M60 x 3 | 3 | 60 | ⌀ 57 | ⌀ 58.5 | 56.752 | |
| M60 x 4 | 4 | 60 | ⌀ 56 | ⌀ 58 | 55.67 | |
| M64 x 2 | 2 | 64 | ⌀ 62 | ⌀ 63 | 61.835 | |
| M64 x 3 | 3 | 64 | ⌀ 61 | ⌀ 63 | 60.752 | |
| M64 x 4 | 4 | 64 | ⌀ 60 | ⌀ 62 | 59.67 | |
| M68 x 2 | 2 | 68 | ⌀ 66 | ⌀ 67 | 65.835 | |
| M68 x 3 | 3 | 68 | ⌀ 65 | ⌀ 67 | 64.752 | |
| M68 x 4 | 4 | 68 | ⌀ 64 | ⌀ 66 | 63.67 | |
| M72 x 2 | 2 | 72 | ⌀ 70 | ⌀ 71 | 69.835 | |
| M72 x 3 | 3 | 72 | ⌀ 69 | ⌀ 71 | 68.752 | |
| M72 x 4 | 4 | 72 | ⌀ 68 | ⌀ 70 | 67.67 | |
| M76 x 2 | 2 | 76 | ⌀ 74 | ⌀ 75 | 73.835 | |
| M76 x 3 | 3 | 76 | ⌀ 73 | ⌀ 75 | 72.752 | |
| M76 x 4 | 4 | 76 | ⌀ 72 | ⌀ 74 | 71.67 | |
| M80 x 2 | 2 | 80 | ⌀ 78 | ⌀ 79 | 77.835 | |
| M80 x 3 | 3 | 80 | ⌀ 77 | ⌀ 79 | 76.752 | |
| M80 x 4 | 4 | 80 | ⌀ 76 | ⌀ 78 | 75.67 | |
| M85 x 2 | 2 | 85 | ⌀ 83 | ⌀ 84 | 82.835 | |
| M85 x 3 | 3 | 85 | ⌀ 82 | ⌀ 84 | 81.752 | |
| M85 x 4 | 4 | 85 | ⌀ 81 | ⌀ 83 | 80.67 | |
| M90 x 2 | 2 | 90 | ⌀ 88 | ⌀ 89 | 87.835 | |
| M90 x 3 | 3 | 90 | ⌀ 87 | ⌀ 89 | 86.752 | |
| M90 x 4 | 4 | 90 | ⌀ 86 | ⌀ 88 | 85.67 | |
| M95 x 2 | 2 | 95 | ⌀ 93 | ⌀ 94 | 92.835 | |
| M95 x 3 | 3 | 95 | ⌀ 92 | ⌀ 94 | 91.752 | |
| M95 x 4 | 4 | 95 | ⌀ 91 | ⌀ 93 | 90.67 | |
| M100 x 2 | 2 | 100 | ⌀ 98 | ⌀ 99 | 97.835 | |
| M100 x 3 | 3 | 100 | ⌀ 97 | ⌀ 99 | 96.752 | |
| M100 x 4 | 4 | 100 | ⌀ 96 | ⌀ 98 | 95.67 |
How to read the chart
Drill for a cutting tap: nominal diameter minus pitch (D − P), rounded to the nearest standard drill, for 75 % thread engagement.
Drill for a forming tap: the tap does not cut, it displaces material, so the hole is larger (approx. D − 0.5·P). Drilling for a cutting tap and then using a forming tap breaks it.
Nut minor Ø: theoretical internal diameter of the ISO profile. Use it to check the hole with a gauge or as the reference for thread milling.
“Calculate” opens the calculator with that size: G84 cycle, feed, blind hole depth and recommended method for the material. Indicative values for 6H/6g threads; for critical parts, check the tap maker's chart.
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