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Metric Bolt & Thread Sizes
Pitch, tap-drill, clearance holes, and hex sizes for M-series bolts.
| Size | Pitch (mm) | Tap drill (mm) | Clearance (mm) | Hex A/F (mm) | Cap key (mm) |
|---|---|---|---|---|---|
| M1.6 | 0.35 | 1.25 | 1.8 | 3.2 | 1.5 |
| M2 | 0.4 | 1.6 | 2.4 | 4 | 1.5 |
| M2.5 | 0.45 | 2.05 | 2.9 | 5 | 2 |
| M3 | 0.5 | 2.5 | 3.4 | 5.5 | 2.5 |
| M4 | 0.7 | 3.3 | 4.5 | 7 | 3 |
| M5 | 0.8 | 4.2 | 5.5 | 8 | 4 |
| M6 | 1 | 5 | 6.6 | 10 | 5 |
| M8 | 1.25 | 6.8 | 9 | 13 | 6 |
| M10 | 1.5 | 8.5 | 11 | 16 | 8 |
| M12 | 1.75 | 10.2 | 13.5 | 18 | 10 |
Tap drill sizes are for standard coarse-pitch threads (~75% thread engagement). Clearanceis the normal-fit through hole. Hex across-flats follows ISO; some DIN parts differ (e.g. M10 hex is 17 mm under DIN 933). Always confirm against your hardware.