Metric Bolt Torque Chart — 8.8, 10.9 and 12.9 (coarse)
Starting assembly torque for ISO 898-1 metric bolts, calculated from T = K × D × F with the clamp load F set at 75% of proof load. Dry uses K = 0.20; lubricated uses K = 0.15. Switch units below.
Not for structural A325 / A490 joints. Match dry or lubricated to the bolt as it is installed.
Torque (N·m)
| Size | 8.8 dry | 10.9 dry | 12.9 dry | 8.8 lubricated | 10.9 lubricated | 12.9 lubricated |
|---|---|---|---|---|---|---|
| M5 x 0.8 | 6.2 | 8.8 | 10 | 4.6 | 6.6 | 7.7 |
| M6 x 1 | 11 | 15 | 18 | 7.9 | 11 | 13 |
| M8 x 1.25 | 25 | 36 | 43 | 19 | 27 | 32 |
| M10 x 1.5 | 50 | 72 | 84 | 38 | 54 | 63 |
| M12 x 1.75 | 88 | 126 | 147 | 66 | 94 | 110 |
| M14 x 2 | 141 | 201 | 235 | 105 | 151 | 176 |
| M16 x 2 | 218 | 312 | 365 | 164 | 234 | 274 |
| M18 x 2.5 | 312 | 431 | 504 | 234 | 323 | 378 |
| M20 x 2.5 | 441 | 610 | 712 | 330 | 457 | 534 |
| M22 x 2.5 | 601 | 831 | 971 | 451 | 623 | 728 |
| M24 x 3 | 761 | 1,053 | 1,231 | 571 | 790 | 923 |
| M27 x 3 | 1,116 | 1,544 | 1,805 | 837 | 1,158 | 1,354 |
| M30 x 3.5 | 1,514 | 2,094 | 2,447 | 1,135 | 1,570 | 1,835 |
| M33 x 3.5 | 2,060 | 2,849 | 3,330 | 1,545 | 2,137 | 2,498 |
| M36 x 4 | 2,646 | 3,661 | 4,278 | 1,985 | 2,745 | 3,208 |
Class 8.8 proof stress is 580 MPa up to M16 and 600 MPa above. Class 9.8 and the low classes are not shown. Pair with nut class 8 / 10 / 12.
Do not use these values for pretensioned or slip-critical structural joints (ASTM F3125 A325 / A490 under RCSC). Those are installed by turn-of-nut, calibrated wrench, twist-off or DTI methods.
Lubrication changes the answer. Applying a dry value to a lubricated, plated or anti-seized bolt can yield or break it. The manufacturer’s or engineer’s value always governs.
How to read this chart: find the size, pick the grade, then pick dry or lubricated to match the bolt as it will actually go in. Worked example — M10 × 1.5 class 8.8, dry: stress area 58.0 mm² × 580 MPa proof = 33.6 kN proof load. Clamp at 75% = 25.2 kN. T = 0.20 × 0.010 m × 25,230 N = 50 N·m (37 ft-lb). Oiled (K 0.15): 38 N·m.
Stress area, proof load and clamp load
| Size | Stress area (mm²) | 8.8 proof load (kN) | 8.8 clamp, 75% (kN) | 10.9 proof load (kN) | 10.9 clamp, 75% (kN) | 12.9 proof load (kN) | 12.9 clamp, 75% (kN) |
|---|---|---|---|---|---|---|---|
| M5 x 0.8 | 14.2 | 8.2 | 6.2 | 11.8 | 8.8 | 13.8 | 10.3 |
| M6 x 1 | 20.1 | 11.7 | 8.8 | 16.7 | 12.5 | 19.5 | 14.6 |
| M8 x 1.25 | 36.6 | 21.2 | 15.9 | 30.4 | 22.8 | 35.5 | 26.6 |
| M10 x 1.5 | 58.0 | 33.6 | 25.2 | 48.1 | 36.1 | 56.2 | 42.2 |
| M12 x 1.75 | 84.3 | 48.9 | 36.7 | 69.9 | 52.5 | 81.7 | 61.3 |
| M14 x 2 | 115.4 | 67.0 | 50.2 | 95.8 | 71.9 | 112.0 | 84.0 |
| M16 x 2 | 156.7 | 90.9 | 68.2 | 130.0 | 97.5 | 152.0 | 114.0 |
| M18 x 2.5 | 192.5 | 115.5 | 86.6 | 159.8 | 119.8 | 186.7 | 140.0 |
| M20 x 2.5 | 244.8 | 146.9 | 110.2 | 203.2 | 152.4 | 237.5 | 178.1 |
| M22 x 2.5 | 303.4 | 182.0 | 136.5 | 251.8 | 188.9 | 294.3 | 220.7 |
| M24 x 3 | 352.5 | 211.5 | 158.6 | 292.6 | 219.4 | 341.9 | 256.4 |
| M27 x 3 | 459.4 | 275.6 | 206.7 | 381.3 | 286.0 | 445.6 | 334.2 |
| M30 x 3.5 | 560.6 | 336.4 | 252.3 | 465.3 | 349.0 | 543.8 | 407.8 |
| M33 x 3.5 | 693.6 | 416.1 | 312.1 | 575.6 | 431.7 | 672.7 | 504.6 |
| M36 x 4 | 816.7 | 490.0 | 367.5 | 677.9 | 508.4 | 792.2 | 594.2 |
K factor: the number that moves the answer
| Condition | Typical K | Note |
|---|---|---|
| Plain steel, dry, as received | 0.20 | This chart’s dry column |
| Zinc plated, dry | 0.17 – 0.22 | Varies with plating and topcoat; many sealers add lubricity |
| Light machine oil | 0.15 – 0.18 | This chart’s lubricated column uses 0.15 |
| Moly paste or anti-seize | 0.10 – 0.13 | Big drop — a dry value here can yield the bolt |
| Stainless on stainless, dry | 0.25 – 0.35 | Galling risk: use anti-seize and tighten slowly |
Typical ranges only. Actual K depends on finish, lubricant, washer, speed and even the batch — test critical joints.
Chart torque converts to actual preload with a scatter of about ±25–30%, because friction varies. Thread-forming and thread-cutting screws have no universal torque — test on the actual joint. Published hex-bolt values are not automatically valid for socket head cap screws.
