SAE Grade 2 vs 5 vs 8
The three inch grades you will see most, compared on one page. The lines on the head are the grade; letters or a logo identify the maker.
SAE J429 comparison
| Grade 2 | Grade 5 | Grade 8 | |
|---|---|---|---|
| Head marking | None (maker ID) | 3 lines, 120 deg | 6 lines, 60 deg |
| Material | Low/medium carbon | Medium carbon, Q&T | Medium carbon alloy, Q&T |
| Size range | 1/4 - 1-1/2 in | 1/4 - 1-1/2 in | 1/4 - 1-1/2 in |
| Proof | 55 / 33 ksi* | 85 / 74 ksi** | 120 ksi |
| Yield (min) | 57 / 36 ksi* | 92 / 81 ksi** | 130 ksi |
| Tensile (min) | 74 / 60 ksi* | 120 / 105 ksi** | 150 ksi |
| Hardness | B80-B100 / B70-B100* | C25-C34 / C19-C30** | C33 - C39 |
| Nut (SAE J995) | Grade 2 | Grade 5 | Grade 8 |
* 1/4 to 3/4 in / over 3/4 to 1-1/2 in. Grade 2 bolts 1/4 - 3/4 in longer than 6 in are supplied with Grade 1 properties (33 / 36 / 60 ksi). ** 1/4 to 1 in / over 1 to 1-1/2 in.
These tables carry the same figures as the printed sheet below.
The printed sheet
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Text version of this sheet
SAE J429 · Grade 2, 5 and 8 side by side
What it is
FIELD IDENTIFICATION
The three inch grades you will see most, compared on one page. The lines on the head are the grade;
letters or a logo identify the maker.
MFG
MFG
MFG
Grade 2
Grade 5
Grade 8
No lines / 3 lines / 6 lines
SAE J429 comparison
Grade 2
Grade 5
Grade 8
Head marking
None (maker ID)
3 lines, 120 deg
6 lines, 60 deg
Material
Low/medium carbon
Medium carbon, Q&T
Medium carbon alloy, Q&T
Size range
1/4 - 1-1/2 in
1/4 - 1-1/2 in
1/4 - 1-1/2 in
Proof
55 / 33 ksi*
85 / 74 ksi**
120 ksi
Yield (min)
57 / 36 ksi*
92 / 81 ksi**
130 ksi
Tensile (min)
74 / 60 ksi*
120 / 105 ksi**
150 ksi
Hardness
B80-B100 / B70-B100*
C25-C34 / C19-C30**
C33 - C39
Nut (SAE J995)
Grade 2
Grade 5
Grade 8
* 1/4 to 3/4 in / over 3/4 to 1-1/2 in. Grade 2 bolts 1/4 - 3/4 in longer than 6 in are supplied with Grade 1 properties (33 / 36 / 60 ksi). ** 1/4 to 1 in / over 1 to 1-1/2 in.
Key points
A blank head is not a reliable Grade 2.
Match the nut grade to the bolt grade.
SAE J429 covers inch bolts and screws up to 1-1/2 in only. It is not a structural (F3125) or pressure/temperature (A193) specification.
Governing standards: SAE J429 (2014); SAE J995 (2017). Editions shown are the latest confirmed as of September 2026. The drawing and the governing standard always take
precedence over this sheet.
torquing any fastener. Verify the current governing standard, project documents, OEM requirements, size, thread, coating and lot certification. To the fullest extent permitted by law, The Fastener App disclaims liability
arising from reliance on this reference.
Fastener Guide reference FG-68259F · thefastenerapp.com/fastener-guide/technical-reference/sae-grade-2-vs-5-vs-8 · © The Fastener App. Reference only — verify the current governing standard, drawing and manufacturer data before specifying or installing.
