Bolt torque chart
Dry tightening torque for coarse-thread steel bolts at 75 % of proof load: metric M4 to M36 in class 8.8, 10.9 and 12.9, and inch 1/4" to 1" in SAE grade 2, 5 and 8. For example, an M10 class 8.8 bolt takes 50 N·m and a 1/2-13 grade 5 bolt takes 75 ft-lb.
Metric bolts
Dry torque in N·m. Open a size for lubricated values, clamp load, wrench size and tap drill.
| Size | Class 8.8 | Class 10.9 | Class 12.9 | Wrench |
|---|---|---|---|---|
| M4 × 0.7 | 3.1 | 4.4 | 5.1 | 7 mm |
| M5 × 0.8 | 6.2 | 8.8 | 10 | 8 mm |
| M6 × 1 | 11 | 15 | 18 | 10 mm |
| M8 × 1.25 | 25 | 36 | 43 | 13 mm |
| M10 × 1.5 | 50 | 72 | 84 | 16 mm |
| M12 × 1.75 | 88 | 126 | 147 | 18 mm |
| M14 × 2 | 141 | 201 | 235 | 21 mm |
| M16 × 2 | 218 | 312 | 365 | 24 mm |
| M18 × 2.5 | 312 | 431 | 504 | 27 mm |
| M20 × 2.5 | 441 | 610 | 712 | 30 mm |
| M22 × 2.5 | 601 | 831 | 971 | 34 mm |
| M24 × 3 | 761 | 1,053 | 1,231 | 36 mm |
| M27 × 3 | 1,116 | 1,544 | 1,805 | 41 mm |
| M30 × 3.5 | 1,514 | 2,094 | 2,447 | 46 mm |
| M33 × 3.5 | 2,060 | 2,849 | 3,330 | 50 mm |
| M36 × 4 | 2,646 | 3,661 | 4,278 | 55 mm |
Inch bolts, UNC
Dry torque in N·m. Each size page also lists UNF threads and lubricated values.
| Size | Grade 2 | Grade 5 | Grade 8 | Wrench |
|---|---|---|---|---|
| 1/4" 20 UNC | 7.4 | 11 | 16 | 7/16" |
| 5/16" 18 UNC | 15 | 24 | 33 | 1/2" |
| 3/8" 16 UNC | 27 | 42 | 59 | 9/16" |
| 7/16" 14 UNC | 43 | 67 | 95 | 5/8" |
| 1/2" 13 UNC | 66 | 102 | 144 | 3/4" |
| 9/16" 12 UNC | 95 | 147 | 208 | 13/16" |
| 5/8" 11 UNC | 132 | 203 | 287 | 15/16" |
| 3/4" 10 UNC | 234 | 361 | 510 | 1-1/8" |
| 7/8" 9 UNC | 226 | 582 | 822 | 1-5/16" |
| 1" 8 UNC | 339 | 873 | 1,232 | 1-1/2" |
Before you tighten
Lubricant changes the number
Oil, moly paste or anti-seize lowers the nut factor K, so the same torque produces far more clamp load. Use the lubricated value whenever the threads are oiled, or the bolt can yield.
Tighten in a star pattern
On flanges and covers, bring every bolt to about 30 %, then 70 %, then full torque, crossing the pattern each pass. Finish with one round at full torque in sequence.
Give the thread enough grip
Engage at least one diameter of thread in steel, about 1.5 diameters in cast iron and 2 diameters in aluminium, or the internal thread strips before the bolt reaches its clamp load.