Metric Bolt → Spanner & Hex Key Converter
Instantly find the right spanner and Allen key size – with Amazon quick-buy links
Quick Lookup
Bolt Size
M5
Spanner Size
8 mm
Hex Key Size
4 mm
| Metric Bolt | Spanner Size | Hex / Allen Key |
|---|---|---|
| M5 | 8 mm | 4 mm |
| M6 | 10 mm | 5 mm |
| M8 | 13 mm | 6 mm |
| M10 | 17 mm | 8 mm |
| M12 | 19 mm | 10 mm |
| M14 | 22 mm | 12 mm |
| M16 | 24 mm | 14 mm |
| M18 | 27 mm | 14 mm |
| M20 | 30 mm | 17 mm |
| M22 | 32 mm | 17 mm |
| M24 | 36 mm | 19 mm |
| M27 | 41 mm | 19 mm |
| M30 | 46 mm | 22 mm |
| M33 | 50 mm | 22 mm |
| M36 | 55 mm | 24 mm |
| M39 | 60 mm | 24 mm |
| M42 | 65 mm | 27 mm |
| M45 | 70 mm | 27 mm |
| M48 | 75 mm | 30 mm |