Carriage Bolts
869 Products
LILY Bearing stocks 869 carriage bolts across seven grade and material options — Grade 2 low-strength steel, Grade 5 and Class 8.8 medium-strength steel, Grade 8 high-strength steel, 18-8 and 316 stainless steel, and silicon bronze — in both square-neck and knurled-neck styles. Use the filters below, or the comparison table, to narrow down by grade, material, thread size, and length.
Compare by Grade & Material
| Grade / Material | Tensile Strength | Best For | Watch Out For |
|---|---|---|---|
| Grade 2 (Low-Strength Steel) | — | Light-duty fastening | About half the strength of Grade 5/Class 8.8 — not for structural loads |
| Grade 5 (Medium-Strength Steel) | 120,000 psi | General machinery and equipment fastening | Twice the strength of Grade 2 — the standard choice for most jobs |
| Class 8.8 (Metric) | 110,000 psi | Metric-spec machinery and equipment | The metric equivalent of Grade 5 — use for metric assemblies |
| Grade 8 (High-Strength Steel) | 150,000 psi | High-stress applications — valves, pumps, motors, automotive suspension | Highest strength tier available — priced accordingly |
| 18-8 Stainless Steel | 70,000 psi | General corrosion and chemical resistance | Lower strength than steel grades — choose for corrosion resistance, not load capacity |
| 316 Stainless Steel | 70,000 psi | Chemical and saltwater exposure | More corrosion-resistant than 18-8 — the choice for marine and harsh-chemical environments |
| Silicon Bronze | — | Saltwater exposure, electrical conductivity, or nonmagnetic requirements | Lower strength than steel — select for corrosion resistance and conductivity, not load capacity |
Square-Neck vs. Knurled-Neck
Most carriage bolts use a square-neck design — the square shank seats into a matching square hole (or embeds itself into wood) to resist turning while the nut is tightened. A knurled-neck design achieves the same anti-rotation function in a plain round hole, using a serrated neck that grips by friction instead. Knurled-neck bolts are available in Low-Strength Steel and Grade 5 Steel.
Need a Custom Carriage Bolt?
Don't see the grade, length, or material you need? Our team can cross-reference an existing part or quote a custom configuration. Request a Quote or Contact Us. LILY Bearing also offers customized fastener services.
Frequently Asked Questions
What is the difference between square-neck and knurled-neck carriage bolts?
A square-neck carriage bolt has a square shank just below the head that seats into a matching square hole (or embeds itself into wood) to keep the bolt from spinning as the nut is tightened. A knurled-neck carriage bolt has a serrated, round neck instead — it grips the sides of a plain round hole by friction, so it doesn't need a square-shaped hole to resist turning.
What is the difference between Grade 5 and Class 8.8 carriage bolts?
Grade 5 and Class 8.8 are equivalent medium-strength tiers — Grade 5 is the inch-based (SAE) designation and Class 8.8 is the metric (DIN/ISO) designation. Both are roughly twice as strong as low-strength (Grade 2) steel; choose Grade 5 for inch-thread assemblies and Class 8.8 for metric-thread assemblies.
