Metric Bolt Head Markings
Printable shop wall chart: Metric Bolt Head Markings. Free letter-size PDF to print and post at the counter; 25 x 36 inch poster version available.
| Marking | Class | Tensile Rm (min) | Yield (min) | Matching nut |
|---|---|---|---|---|
| 4.6 | 4.6 | 400 MPa | 240 MPa | 5 |
| 4.8 | 4.8 | 420 MPa | 340 MPa | 5 |
| 5.8 | 5.8 | 520 MPa | 420 MPa | 5 |
| 8.8 | 8.8 | 800 / 830 MPa | 640 / 660 MPa | 8 |
| 9.8 | 9.8 (to M16) | 900 MPa | 720 MPa | 9 |
| 10.9 | 10.9 | 1040 MPa | 940 MPa | 10 |
| 12.9 | 12.9 (usually socket heads) | 1220 MPa | 1100 MPa | 12 |
8.8 values: up to M16 / over M16. Marking is required on property class 8.8 and above from M5. Stainless metric uses ISO 3506 marks such as A2-70.
These tables carry the same figures as the printed sheet below.
The printed sheet
25 x 36 inch poster version
For the full-size shop poster, tell us where to send it.
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Text version of this sheet
4.6
4.8
5.8
8.8
9.8
10.9
CLASS 4.6
CLASS 4.8
CLASS 5.8
CLASS 8.8
CLASS 9.8
CLASS 10.9
12.9
12.9 (TYP. SOCKET)
ISO 898-1 property classes · class number plus manufacturer mark
Marking
Class
Tensile Rm (min)
Yield (min)
Matching nut
4.6
4.6
400 MPa
240 MPa
5
4.8
4.8
420 MPa
340 MPa
5
5.8
5.8
520 MPa
420 MPa
5
8.8
8.8
800 / 830 MPa
640 / 660 MPa
8
9.8
9.8 (to M16)
900 MPa
720 MPa
9
10.9
10.9
1040 MPa
940 MPa
10
12.9
12.9 (usually socket heads)
1220 MPa
1100 MPa
12
8.8 values: up to M16 / over M16. Marking is required on property class 8.8 and above from M5. Stainless metric uses ISO 3506 marks such as A2-70.
The Fastener App | TheFastenerApp.com
Fastener Guide reference FG-A1DB62 · thefastenerapp.com/fastener-guide/wall-charts/metric-bolt-head-markings · © The Fastener App. Reference only — verify the current governing standard, drawing and manufacturer data before specifying or installing.
