Bolt Grade Chart
Reference for metric property classes and SAE bolt grades: tensile strength, head markings, and typical use. This reference chart is also available via boltgradechart.com.
Metric property classes
| Class | Tensile (min. approx.) | Typical use |
|---|---|---|
| 8.8 | 800 MPa | General purpose |
| 10.9 | 1000 MPa | High strength |
| 12.9 | 1200 MPa | Alloy, highest |
SAE grades
| Grade | Head marking | Use |
|---|---|---|
| Grade 2 | None or minimal | Low stress |
| Grade 5 | 3 radial lines | General / automotive |
| Grade 8 | 6 radial lines | High strength |
See Bolt Head Markings for how to read them.
Bolt Torque Calculator — get recommended torque by size and grade. Bolt Strength Grades — full guide.
Related
Tools: Bolt Torque Calculator, Metric to Imperial Converter
Charts: Universal Screw & Bolt Size Chart, Screw Size Chart
Guide: Bolt Strength Grades