Metric fastener size chart
Dimensions for socket head cap screws, hex bolts and hex nuts from M3 to M24, plus tap drill and clearance hole sizes.
Size finder
Choose a thread size, or see the full size chart.
Dimensions in mm. Coarse pitch. Cap screw per ISO 4762, hex bolt per ISO 4017, hex nut style 1 per ISO 4032, clearance hole medium series per ISO 273.
Full tables
| Thread | Pitch | Head dia. (dk) | Head height (k) | Hex key (s) |
|---|---|---|---|---|
| M3 | 0.5 | 5.5 | 3 | 2.5 |
| M4 | 0.7 | 7 | 4 | 3 |
| M5 | 0.8 | 8.5 | 5 | 4 |
| M6 | 1 | 10 | 6 | 5 |
| M8 | 1.25 | 13 | 8 | 6 |
| M10 | 1.5 | 16 | 10 | 8 |
| M12 | 1.75 | 18 | 12 | 10 |
| M14 | 2 | 21 | 14 | 12 |
| M16 | 2 | 24 | 16 | 14 |
| M20 | 2.5 | 30 | 20 | 17 |
| M24 | 3 | 36 | 24 | 19 |
| Thread | Pitch | Across flats (s) | Head height (k) |
|---|---|---|---|
| M3 | 0.5 | 5.5 | 2 |
| M4 | 0.7 | 7 | 2.8 |
| M5 | 0.8 | 8 | 3.5 |
| M6 | 1 | 10 | 4 |
| M8 | 1.25 | 13 | 5.3 |
| M10 | 1.5 | 16 | 6.4 |
| M12 | 1.75 | 18 | 7.5 |
| M14 | 2 | 21 | 8.8 |
| M16 | 2 | 24 | 10 |
| M20 | 2.5 | 30 | 12.5 |
| M24 | 3 | 36 | 15 |
| Thread | Pitch | Across flats (s) | Thickness (m) |
|---|---|---|---|
| M3 | 0.5 | 5.5 | 2.4 |
| M4 | 0.7 | 7 | 3.2 |
| M5 | 0.8 | 8 | 4.7 |
| M6 | 1 | 10 | 5.2 |
| M8 | 1.25 | 13 | 6.8 |
| M10 | 1.5 | 16 | 8.4 |
| M12 | 1.75 | 18 | 10.8 |
| M14 | 2 | 21 | 12.8 |
| M16 | 2 | 24 | 14.8 |
| M20 | 2.5 | 30 | 18 |
| M24 | 3 | 36 | 21.5 |
| Thread | Tap drill | Clearance hole (medium, ISO 273) |
|---|---|---|
| M3 | 2.5 | 3.4 |
| M4 | 3.3 | 4.5 |
| M5 | 4.2 | 5.5 |
| M6 | 5 | 6.6 |
| M8 | 6.8 | 9 |
| M10 | 8.5 | 11 |
| M12 | 10.2 | 13.5 |
| M14 | 12 | 15.5 |
| M16 | 14 | 17.5 |
| M20 | 17.5 | 22 |
| M24 | 21 | 26 |
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