Engineering quick reference
Bolt Torque Chart
Recommended assembly torque for SAE Grade 2/5/8, ISO 8.8/10.9/12.9, and stainless A2-70 fasteners — dry and lubricated.
| Size | Aₜ in² | Recommended assembly torque — ft-lb @ 75% yield preload | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| SAE Grade 2inch only57 ksi yield | SAE Grade 5metric: ISO 8.892 ksi yield | SAE Grade 8metric: ISO 10.9130 / 136 ksi yield | ISO 12.9160 ksi yield | A2-70 SS65 ksi yield | |||||||
| Dry | Oiled | Dry | Oiled | Dry | Oiled | Dry | Oiled | Dry | Oiled | ||
| Inch — Unified coarse (UNC) | |||||||||||
| 1/4-20 | 0.0318 | 5.7 | 4.2 | 9.1 | 6.9 | 13 | 9.7 | 16 | 12 | 6.5 | 4.8 |
| 5/16-18 | 0.0524 | 12 | 8.8 | 19 | 14 | 27 | 20 | 33 | 25 | 13 | 10.0 |
| 3/8-16 | 0.0775 | 21 | 16 | 33 | 25 | 47 | 35 | 58 | 44 | 24 | 18 |
| 7/16-14 | 0.1063 | 33 | 25 | 53 | 40 | 76 | 57 | 93 | 70 | 38 | 28 |
| 1/2-13 | 0.1419 | 51 | 38 | 82 | 61 | 115 | 86 | 142 | 106 | 58 | 43 |
| 9/16-12 | 0.1820 | 73 | 55 | 118 | 88 | 166 | 125 | 205 | 154 | 83 | 62 |
| 5/8-11 | 0.2260 | 101 | 75 | 162 | 122 | 230 | 172 | 283 | 212 | 115 | 86 |
| 3/4-10 | 0.3340 | 178 | 134 | 288 | 216 | 407 | 305 | 501 | 376 | 204 | 153 |
| 7/8-9 | 0.4620 | 182 | 136 | 465 | 349 | 657 | 493 | 809 | 606 | 328 | 246 |
| 1-8 | 0.6060 | 273 | 205 | 697 | 523 | 985 | 739 | 1,212 | 909 | 492 | 369 |
| Metric — ISO coarse | |||||||||||
| M5 | 0.0220 | — | — | 5.0 | 3.7 | 7.4 | 5.5 | 8.7 | 6.5 | 3.5 | 2.6 |
| M6 | 0.0312 | — | — | 8.5 | 6.4 | 13 | 9.4 | 15 | 11 | 6.0 | 4.5 |
| M8 | 0.0568 | — | — | 21 | 15 | 30 | 23 | 36 | 27 | 15 | 11 |
| M10 | 0.0900 | — | — | 41 | 31 | 60 | 45 | 71 | 53 | 29 | 22 |
| M12 | 0.1310 | — | — | 71 | 53 | 105 | 79 | 124 | 93 | 50 | 38 |
| M16 | 0.2430 | — | — | 176 | 132 | 260 | 195 | 306 | 230 | 124 | 93 |
| M20 | 0.3800 | — | — | 344 | 258 | 509 | 381 | 598 | 449 | 243 | 182 |
Key:all values in ft-lb at 75% of yield preload.Dry = uncoated steel-on-steel, K = 0.20.Oiled = light oil / wax, K = 0.15.Aₜ = thread tensile stress area (in²).
T = K × D × F, where F = 0.75 × yield × tensile area. SAE Grade 5 (92 ksi) ≈ ISO 8.8 (92 ksi); SAE Grade 8 (130 ksi) ≈ ISO 10.9 (136 ksi) — metric rows in those columns are computed at the ISO value. Grade 2 is inch-only (— on metric rows). A2-70 = 304 stainless. Per SAE J429, Grade 2 yield drops to 36 ksi over 3/4″ dia — the 7/8-9 and 1-8 rows use 36 ksi.
Reduce torque 30–50% in tapped holes of soft material (aluminum, plastics) to protect the threads. For lubrication factors not shown (zinc K = 0.18, anti-seize K = 0.12, PTFE K = 0.09) and any size, grade, or preload combination, use the interactivebolt torque calculator.
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