ASTM A307 Bolt Torque Chart
Tightening torque and clamp force for ASTM A307 bolts from 1/4" to 2". For example, a 1/4" A307 bolt needs about 3.56 ft·lb (4.83 N·m) with dry threads.
Low-carbon steel for general construction, anchor bolts and non-structural connections. ASTM A307 has no minimum yield; 36 ksi is assumed.
- Standard
- ASTM (inch)
- Yield strength used
- 250 MPa (36 ksi)
- Tensile strength
- 414 MPa (60 ksi)
- Sizes covered
- 1/4" – 2"
| Size | Threadpitch | Clamp forcepreload | Dryμ 0.15 | Oiledμ 0.11 | PTFE / moly pasteμ 0.06 |
|---|---|---|---|---|---|
| 1/4" | 1/4"-20 UNC20 TPI | 3.59 kN808 lbf | 3.56 ft·lb4.83 N·m | 2.70 ft·lb3.66 N·m | 1.84 ft·lb2.50 N·m |
| 5/16" | 5/16"-18 UNC18 TPI | 5.92 kN1331 lbf | 7.03 ft·lb9.53 N·m | 5.31 ft·lb7.21 N·m | 3.60 ft·lb4.88 N·m |
| 3/8" | 3/8"-16 UNC16 TPI | 8.75 kN1967 lbf | 12.1 ft·lb16.5 N·m | 9.15 ft·lb12.4 N·m | 6.17 ft·lb8.37 N·m |
| 7/16" | 7/16"-14 UNC14 TPI | 12.0 kN2698 lbf | 19.1 ft·lb25.9 N·m | 14.4 ft·lb19.5 N·m | 9.70 ft·lb13.2 N·m |
| 1/2" | 1/2"-13 UNC13 TPI | 16.0 kN3602 lbf | 29.7 ft·lb40.2 N·m | 22.3 ft·lb30.2 N·m | 14.9 ft·lb20.2 N·m |
| 9/16" | 9/16"-12 UNC12 TPI | 20.5 kN4618 lbf | 42.1 ft·lb57.1 N·m | 31.6 ft·lb42.8 N·m | 21.1 ft·lb28.6 N·m |
| 5/8" | 5/8"-11 UNC11 TPI | 25.5 kN5736 lbf | 58.5 ft·lb79.3 N·m | 43.9 ft·lb59.5 N·m | 29.2 ft·lb39.6 N·m |
| 3/4" | 3/4"-10 UNC10 TPI | 37.8 kN8489 lbf | 102.9 ft·lb139.5 N·m | 76.9 ft·lb104.3 N·m | 50.9 ft·lb69.0 N·m |
| 7/8" | 7/8"-9 UNC9 TPI | 52.1 kN11720 lbf | 164.8 ft·lb223.5 N·m | 122.9 ft·lb166.7 N·m | 81.0 ft·lb109.9 N·m |
| 1" | 1"-8 UNC8 TPI | 68.4 kN15375 lbf | 246.4 ft·lb334.1 N·m | 183.7 ft·lb249.1 N·m | 121.0 ft·lb164.0 N·m |
| 1-1/8" | 1-1/8"-7 UNC7 TPI | 86.2 kN19373 lbf | 349.2 ft·lb473.5 N·m | 260.5 ft·lb353.2 N·m | 171.8 ft·lb232.9 N·m |
| 1-1/4" | 1-1/4"-7 UNC7 TPI | 109.4 kN24598 lbf | 488.8 ft·lb662.7 N·m | 363.2 ft·lb492.5 N·m | 237.7 ft·lb322.2 N·m |
| 1-3/8" | 1-3/8"-6 UNC6 TPI | 130.4 kN29313 lbf | 642.6 ft·lb871.2 N·m | 478.5 ft·lb648.8 N·m | 314.5 ft·lb426.4 N·m |
| 1-1/2" | 1-1/2"-6 UNC6 TPI | 158.7 kN35667 lbf | 847.6 ft·lb1149.2 N·m | 629.3 ft·lb853.3 N·m | 411.1 ft·lb557.3 N·m |
| 1-3/4" | 1-3/4"-5 UNC5 TPI | 214.5 kN48211 lbf | 1337.5 ft·lb1813.4 N·m | 994.0 ft·lb1347.7 N·m | 650.6 ft·lb882.1 N·m |
| 2" | 2"-4.5 UNC4.5 TPI | 282.1 kN63409 lbf | 2005.1 ft·lb2718.6 N·m | 1488.9 ft·lb2018.6 N·m | 972.6 ft·lb1318.7 N·m |
| Size | Threadpitch | Clamp forcepreload | Dryμ 0.15 | Oiledμ 0.11 | PTFE / moly pasteμ 0.06 |
|---|---|---|---|---|---|
| 1/4" | 1/4"-28 UNF28 TPI | 4.11 kN923 lbf | 3.96 ft·lb5.36 N·m | 2.96 ft·lb4.01 N·m | 1.96 ft·lb2.65 N·m |
| 5/16" | 5/16"-24 UNF24 TPI | 6.56 kN1474 lbf | 7.61 ft·lb10.3 N·m | 5.68 ft·lb7.70 N·m | 3.75 ft·lb5.09 N·m |
| 3/8" | 3/8"-24 UNF24 TPI | 9.92 kN2229 lbf | 13.4 ft·lb18.1 N·m | 9.91 ft·lb13.4 N·m | 6.47 ft·lb8.77 N·m |
| 7/16" | 7/16"-20 UNF20 TPI | 13.4 kN3013 lbf | 20.8 ft·lb28.1 N·m | 15.4 ft·lb20.9 N·m | 10.1 ft·lb13.7 N·m |
| 1/2" | 1/2"-20 UNF20 TPI | 18.1 kN4060 lbf | 32.5 ft·lb44.0 N·m | 24.0 ft·lb32.6 N·m | 15.6 ft·lb21.1 N·m |
| 9/16" | 9/16"-18 UNF18 TPI | 22.9 kN5152 lbf | 45.7 ft·lb62.0 N·m | 33.8 ft·lb45.9 N·m | 21.9 ft·lb29.7 N·m |
| 5/8" | 5/8"-18 UNF18 TPI | 28.9 kN6497 lbf | 64.3 ft·lb87.1 N·m | 47.4 ft·lb64.2 N·m | 30.5 ft·lb41.3 N·m |
| 3/4" | 3/4"-16 UNF16 TPI | 42.1 kN9466 lbf | 111.7 ft·lb151.4 N·m | 82.2 ft·lb111.4 N·m | 52.7 ft·lb71.5 N·m |
| 7/8" | 7/8"-14 UNF14 TPI | 57.5 kN12931 lbf | 177.4 ft·lb240.5 N·m | 130.5 ft·lb176.9 N·m | 83.6 ft·lb113.3 N·m |
| 1" | 1"-12 UNF12 TPI | 74.9 kN16829 lbf | 263.6 ft·lb357.4 N·m | 194.0 ft·lb263.1 N·m | 124.5 ft·lb168.7 N·m |
| 1-1/8" | 1-1/8"-12 UNF12 TPI | 96.6 kN21720 lbf | 380.3 ft·lb515.6 N·m | 279.1 ft·lb378.4 N·m | 177.9 ft·lb241.2 N·m |
| 1-1/4" | 1-1/4"-12 UNF12 TPI | 121.1 kN27233 lbf | 527.0 ft·lb714.5 N·m | 385.9 ft·lb523.2 N·m | 244.8 ft·lb331.8 N·m |
| 1-3/8" | 1-3/8"-12 UNF12 TPI | 148.4 kN33369 lbf | 707.2 ft·lb958.9 N·m | 516.9 ft·lb700.8 N·m | 326.5 ft·lb442.6 N·m |
| 1-1/2" | 1-1/2"-12 UNF12 TPI | 178.5 kN40129 lbf | 924.5 ft·lb1253.4 N·m | 674.5 ft·lb914.5 N·m | 424.5 ft·lb575.6 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" A307 bolt?
About 3.56 ft·lb (4.83 N·m) with dry threads and 2.70 ft·lb (3.66 N·m) with oiled threads (1/4"-20 UNC, 70% of yield, clamp force 3.59 kN).
What is the torque for a 3/8" A307 bolt?
About 12.1 ft·lb (16.5 N·m) with dry threads and 9.15 ft·lb (12.4 N·m) with oiled threads (3/8"-16 UNC, 70% of yield, clamp force 8.75 kN).
What is the torque for a 1/2" A307 bolt?
About 29.7 ft·lb (40.2 N·m) with dry threads and 22.3 ft·lb (30.2 N·m) with oiled threads (1/2"-13 UNC, 70% of yield, clamp force 16.0 kN).