Thread tables
Outside Ø, pitch/TPI, tap drill (75 %) and core diameter per standard.
MetricMetric fineUNCUNFUNEFBSW (Whitworth)BSF (Whitworth fine)NPT (tapered)BSPP / GACMETrapezoidal (DIN 103)STI (Helicoil)
| Threads | Outside ⌀ [mm] | Pitch [mm] | Tap drill 75 % [mm] | Core Ø [mm] |
|---|---|---|---|---|
| M1 | 1.0 | 0.25 | 0.76 | 0.729 |
| M1.2 | 1.2 | 0.25 | 0.96 | 0.929 |
| M1.6 | 1.6 | 0.35 | 1.26 | 1.221 |
| M2 | 2.0 | 0.4 | 1.61 | 1.567 |
| M2.5 | 2.5 | 0.45 | 2.06 | 2.013 |
| M3 | 3.0 | 0.5 | 2.51 | 2.459 |
| M4 | 4.0 | 0.7 | 3.32 | 3.242 |
| M5 | 5.0 | 0.8 | 4.22 | 4.134 |
| M6 | 6.0 | 1.0 | 5.03 | 4.918 |
| M8 | 8.0 | 1.25 | 6.78 | 6.647 |
| M10 | 10.0 | 1.5 | 8.54 | 8.376 |
| M12 | 12.0 | 1.75 | 10.3 | 10.106 |
| M14 | 14.0 | 2.0 | 12.05 | 11.835 |
| M16 | 16.0 | 2.0 | 14.05 | 13.835 |
| M18 | 18.0 | 2.5 | 15.56 | 15.294 |
| M20 | 20.0 | 2.5 | 17.56 | 17.294 |
| M22 | 22.0 | 2.5 | 19.56 | 19.294 |
| M24 | 24.0 | 3.0 | 21.08 | 20.753 |
| M27 | 27.0 | 3.0 | 24.08 | 23.753 |
| M30 | 30.0 | 3.5 | 26.59 | 26.211 |
| M33 | 33.0 | 3.5 | 29.59 | 29.211 |
| M36 | 36.0 | 4.0 | 32.1 | 31.67 |
| M39 | 39.0 | 4.0 | 35.1 | 34.67 |
| M42 | 42.0 | 4.5 | 37.62 | 37.129 |
| M48 | 48.0 | 5.0 | 43.13 | 42.587 |
| M56 | 56.0 | 5.5 | 50.64 | 50.046 |
| M64 | 64.0 | 6.0 | 58.15 | 57.505 |
Tap drill for cutting tap at 75 % flank engagement. UN/metric: 60°; Whitworth: 55°; NPT: tapered 1:16 (bore Ø per ANSI B1.20.1); ACME: 29°, trapezoidal DIN 103: 30° Lead screw thread (tap drill = core Ø = D − P, ideal dimension). All values are guideline values.
Note: all cutting and material values are guide values. The tool or machine manufacturer's recommendations are decisive.
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