Nuts & Wrench Sizes — Complete Reference
Complete reference for metric hex nuts from M3 to M20. Wrench sizes, thickness, and specifications.
M35.5 mm wrench · 2.4 mm thickM47 mm wrench · 3.2 mm thickM58 mm wrench · 4 mm thickM610 mm wrench · 5 mm thickM813 mm wrench · 6.5 mm thickM1017 mm wrench · 8 mm thickM1219 mm wrench · 10 mm thickM1624 mm wrench · 13 mm thickM2030 mm wrench · 16 mm thick
About metric nuts
Metric hex nuts are designated by their nominal diameter (e.g., M8 = 8mm). The wrench size is measured across the flats of the hexagon.
Nut standards
- ISO 4032: Standard hex nut (most common)
- ISO 4033: Hex nut, style 2 (taller)
- ISO 4035: Hex thin nut
- ISO 7040: Hex nut with nylon insert (lock nut)
Nut grades
- Class 4: Low strength
- Class 8: Medium strength (most common)
- Class 10: High strength
- Class 12: Very high strength