SAE Grade 8 Bolt Torque Chart
Tightening torque and clamp force for SAE Grade 8 bolts from 1/4" to 1-1/2". For example, a 1/4" Grade 8 bolt needs about 12.8 ft·lb (17.3 N·m) with dry threads.
Medium-carbon alloy steel, quenched and tempered, 6 radial lines on the head. For high-stress joints in vehicles and machinery.
- Standard
- SAE J429 (inch)
- Yield strength used
- 896 MPa (130 ksi)
- Tensile strength
- 1034 MPa (150 ksi)
- Sizes covered
- 1/4" – 1-1/2"
| Size | Threadpitch | Clamp forcepreload | Dryμ 0.15 | Oiledμ 0.11 | PTFE / moly pasteμ 0.06 |
|---|---|---|---|---|---|
| 1/4" | 1/4"-20 UNC20 TPI | 12.9 kN2895 lbf | 12.8 ft·lb17.3 N·m | 9.69 ft·lb13.1 N·m | 6.61 ft·lb8.96 N·m |
| 5/16" | 5/16"-18 UNC18 TPI | 21.2 kN4769 lbf | 25.2 ft·lb34.2 N·m | 19.0 ft·lb25.8 N·m | 12.9 ft·lb17.5 N·m |
| 3/8" | 3/8"-16 UNC16 TPI | 31.4 kN7049 lbf | 43.5 ft·lb59.0 N·m | 32.8 ft·lb44.5 N·m | 22.1 ft·lb30.0 N·m |
| 7/16" | 7/16"-14 UNC14 TPI | 43.0 kN9671 lbf | 68.4 ft·lb92.8 N·m | 51.6 ft·lb70.0 N·m | 34.8 ft·lb47.2 N·m |
| 1/2" | 1/2"-13 UNC13 TPI | 57.4 kN12908 lbf | 106.3 ft·lb144.1 N·m | 79.9 ft·lb108.3 N·m | 53.4 ft·lb72.4 N·m |
| 9/16" | 9/16"-12 UNC12 TPI | 73.6 kN16551 lbf | 150.9 ft·lb204.6 N·m | 113.3 ft·lb153.6 N·m | 75.6 ft·lb102.5 N·m |
| 5/8" | 5/8"-11 UNC11 TPI | 91.5 kN20559 lbf | 209.7 ft·lb284.3 N·m | 157.2 ft·lb213.2 N·m | 104.7 ft·lb142.0 N·m |
| 3/4" | 3/4"-10 UNC10 TPI | 135.3 kN30425 lbf | 368.9 ft·lb500.1 N·m | 275.6 ft·lb373.6 N·m | 182.3 ft·lb247.2 N·m |
| 7/8" | 7/8"-9 UNC9 TPI | 186.8 kN42003 lbf | 590.7 ft·lb800.9 N·m | 440.6 ft·lb597.3 N·m | 290.4 ft·lb393.8 N·m |
| 1" | 1"-8 UNC8 TPI | 245.1 kN55103 lbf | 883.2 ft·lb1197.4 N·m | 658.4 ft·lb892.6 N·m | 433.6 ft·lb587.8 N·m |
| 1-1/8" | 1-1/8"-7 UNC7 TPI | 308.9 kN69433 lbf | 1251.7 ft·lb1697.0 N·m | 933.7 ft·lb1265.9 N·m | 615.6 ft·lb834.7 N·m |
| 1-1/4" | 1-1/4"-7 UNC7 TPI | 392.1 kN88158 lbf | 1751.7 ft·lb2375.0 N·m | 1301.8 ft·lb1765.0 N·m | 851.8 ft·lb1154.9 N·m |
| 1-3/8" | 1-3/8"-6 UNC6 TPI | 467.3 kN105057 lbf | 2303.0 ft·lb3122.4 N·m | 1715.0 ft·lb2325.3 N·m | 1127.1 ft·lb1528.2 N·m |
| 1-1/2" | 1-1/2"-6 UNC6 TPI | 568.6 kN127832 lbf | 3037.9 ft·lb4118.8 N·m | 2255.5 ft·lb3058.1 N·m | 1473.2 ft·lb1997.4 N·m |
| Size | Threadpitch | Clamp forcepreload | Dryμ 0.15 | Oiledμ 0.11 | PTFE / moly pasteμ 0.06 |
|---|---|---|---|---|---|
| 1/4" | 1/4"-28 UNF28 TPI | 14.7 kN3309 lbf | 14.2 ft·lb19.2 N·m | 10.6 ft·lb14.4 N·m | 7.02 ft·lb9.51 N·m |
| 5/16" | 5/16"-24 UNF24 TPI | 23.5 kN5282 lbf | 27.3 ft·lb37.0 N·m | 20.4 ft·lb27.6 N·m | 13.4 ft·lb18.2 N·m |
| 3/8" | 3/8"-24 UNF24 TPI | 35.5 kN7990 lbf | 47.8 ft·lb64.9 N·m | 35.5 ft·lb48.2 N·m | 23.2 ft·lb31.4 N·m |
| 7/16" | 7/16"-20 UNF20 TPI | 48.0 kN10799 lbf | 74.4 ft·lb100.8 N·m | 55.3 ft·lb75.0 N·m | 36.2 ft·lb49.1 N·m |
| 1/2" | 1/2"-20 UNF20 TPI | 64.7 kN14551 lbf | 116.4 ft·lb157.8 N·m | 86.1 ft·lb116.7 N·m | 55.8 ft·lb75.6 N·m |
| 9/16" | 9/16"-18 UNF18 TPI | 82.1 kN18465 lbf | 163.9 ft·lb222.2 N·m | 121.2 ft·lb164.3 N·m | 78.5 ft·lb106.5 N·m |
| 5/8" | 5/8"-18 UNF18 TPI | 103.6 kN23284 lbf | 230.3 ft·lb312.3 N·m | 169.8 ft·lb230.2 N·m | 109.3 ft·lb148.1 N·m |
| 3/4" | 3/4"-16 UNF16 TPI | 150.9 kN33927 lbf | 400.2 ft·lb542.6 N·m | 294.5 ft·lb399.4 N·m | 188.9 ft·lb256.1 N·m |
| 7/8" | 7/8"-14 UNF14 TPI | 206.2 kN46346 lbf | 635.7 ft·lb861.9 N·m | 467.7 ft·lb634.1 N·m | 299.6 ft·lb406.2 N·m |
| 1" | 1"-12 UNF12 TPI | 268.3 kN60315 lbf | 944.8 ft·lb1281.0 N·m | 695.4 ft·lb942.9 N·m | 446.1 ft·lb604.8 N·m |
| 1-1/8" | 1-1/8"-12 UNF12 TPI | 346.3 kN77843 lbf | 1362.9 ft·lb1847.8 N·m | 1000.2 ft·lb1356.2 N·m | 637.6 ft·lb864.5 N·m |
| 1-1/4" | 1-1/4"-12 UNF12 TPI | 434.2 kN97603 lbf | 1888.7 ft·lb2560.8 N·m | 1383.0 ft·lb1875.0 N·m | 877.2 ft·lb1189.3 N·m |
| 1-3/8" | 1-3/8"-12 UNF12 TPI | 532.0 kN119596 lbf | 2534.8 ft·lb3436.7 N·m | 1852.4 ft·lb2511.5 N·m | 1170.1 ft·lb1586.4 N·m |
| 1-1/2" | 1-1/2"-12 UNF12 TPI | 639.8 kN143822 lbf | 3313.3 ft·lb4492.2 N·m | 2417.4 ft·lb3277.6 N·m | 1521.5 ft·lb2062.9 N·m |
Preload is 70% of yield. Torque per ISO 16047 / VDI 2230 for standard hex heads, with the same friction μ in the threads and under the head. Click a size for wrench size, tap drill and a worked example. Always follow the manufacturer's value where one exists.
Frequently asked questions
What is the torque for a 1/4" Grade 8 bolt?
About 12.8 ft·lb (17.3 N·m) with dry threads and 9.69 ft·lb (13.1 N·m) with oiled threads (1/4"-20 UNC, 70% of yield, clamp force 12.9 kN).
What is the torque for a 3/8" Grade 8 bolt?
About 43.5 ft·lb (59.0 N·m) with dry threads and 32.8 ft·lb (44.5 N·m) with oiled threads (3/8"-16 UNC, 70% of yield, clamp force 31.4 kN).
What is the torque for a 1/2" Grade 8 bolt?
About 106.3 ft·lb (144.1 N·m) with dry threads and 79.9 ft·lb (108.3 N·m) with oiled threads (1/2"-13 UNC, 70% of yield, clamp force 57.4 kN).