Torque Reference Guide
Recommended bolt load and tightening torque for metric coarse, UNC and UNF threads by grade, with surface condition correction factors and the formulae used.
Recommendation notice
The values on this page are general recommendations for the operating conditions stated below and are conservative. They are intended as a starting reference only. For critical or safety-related applications, the tightening torque must be validated with the fastener manufacturer before use. For assistance in selecting a torque wrench, please use the Torque Wrench Selector.
Operational assumptions
- ConditionBolts and nuts are new, standard finish, uncoated and unlubricated.
- Loading90% of bolt yield strength.
- Friction coefficient (µ)0.14
- TechniqueTightening is smooth and slow.
Metric coarse threads (M2 to M42)
Load in newtons (N) and tightening torque in newton metres (N·m) for each property class. A/F = across flats.
| Size | Grade 3.6 | Grade 5.6 | Grade 6.9 | Grade 8.8 | Grade 10.9 | Grade 12.9 | A/F (mm) | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Load (N) | Torque (N·m) | Load (N) | Torque (N·m) | Load (N) | Torque (N·m) | Load (N) | Torque (N·m) | Load (N) | Torque (N·m) | Load (N) | Torque (N·m) | ||
| M2 | 284 | 0.12 | 378 | 0.16 | 731 | 0.31 | 863 | 0.37 | 1,216 | 0.52 | 1,461 | 0.63 | 4 |
| M3 | 726 | 0.44 | 966 | 0.59 | 1,863 | 1.13 | 2,206 | 1.34 | 3,109 | 1.88 | 3,727 | 2.26 | 5.5 |
| M4 | 1,255 | 1.00 | 1,677 | 1.34 | 3,226 | 2.60 | 3,825 | 3.04 | 5,374 | 4.31 | 6,453 | 5.15 | 7 |
| M5 | 2,059 | 1.96 | 2,736 | 2.65 | 5,286 | 5.10 | 6,257 | 6.03 | 8,806 | 8.48 | 10,591 | 10.2 | 8 |
| M6 | 2,903 | 3.43 | 3,864 | 4.51 | 7,453 | 8.73 | 8,836 | 10.3 | 12,405 | 14.7 | 14,906 | 17.6 | 10 |
| M8 | 5,315 | 8.24 | 7,090 | 10.7 | 13,680 | 21.5 | 16,230 | 25.5 | 22,751 | 35.3 | 27,360 | 42.1 | 13 |
| M10 | 8,473 | 16.7 | 11,278 | 21.5 | 21,771 | 42.1 | 25,791 | 50.0 | 36,284 | 70.6 | 43,541 | 85.3 | 17 |
| M12 | 12,356 | 28.4 | 16,475 | 38.2 | 31,773 | 73.5 | 37,657 | 87.2 | 52,956 | 122 | 63,547 | 147 | 19 |
| M16 | 23,340 | 69.6 | 31,087 | 93.1 | 60,016 | 178 | 71,196 | 210 | 100,027 | 299 | 120,131 | 357 | 24 |
| M20 | 36,481 | 135 | 48,641 | 180 | 93,849 | 347 | 111,305 | 411 | 156,415 | 578 | 187,796 | 696 | 30 |
| M24 | 52,563 | 230 | 70,019 | 308 | 135,331 | 598 | 160,338 | 711 | 225,552 | 1,000 | 270,662 | 1,196 | 36 |
| M30 | 84,043 | 466 | 112,286 | 622 | 215,745 | 1,206 | 255,952 | 1,422 | 359,902 | 2,010 | 432,471 | 2,403 | 46 |
| M36 | 123,073 | 814 | 164,261 | 1,089 | 316,753 | 2,099 | 374,612 | 2,481 | 527,595 | 3,491 | 633,100 | 4,197 | 55 |
| M42 | 169,164 | 1,304 | 225,552 | 1,746 | 435,413 | 3,364 | 515,827 | 3,991 | 725,688 | 5,609 | 870,826 | 6,727 | 65 |
Swipe the table sideways to see all columns.
To choose a torque wrench for these values, see suitable torque wrenches below.
UNC threads (Unified National Coarse)
Load in newtons (N) and tightening torque in newton metres (N·m) for Grades P, S and T. A/F = across flats.
| Size (in) | Grade P | Grade S | Grade T | A/F (in) | |||
|---|---|---|---|---|---|---|---|
| Load (N) | Torque (N·m) | Load (N) | Torque (N·m) | Load (N) | Torque (N·m) | ||
| 1/4 | 4,379 | 5.43 | 8,320 | 10.3 | 8,980 | 11.1 | 7/16 |
| 5/16 | 7,344 | 11.2 | 13,954 | 21.3 | 15,061 | 23.0 | 1/2 |
| 3/8 | 10,951 | 19.9 | 20,807 | 37.9 | 22,458 | 40.9 | 9/16 |
| 7/16 | 15,065 | 31.9 | 28,623 | 60.7 | 30,894 | 65.5 | 5/8 |
| 1/2 | 20,244 | 48.8 | 38,463 | 92.7 | 41,516 | 100 | 3/4 |
| 9/16 | 26,075 | 70.4 | 49,542 | 134 | 53,474 | 144 | 13/16 |
| 5/8 | 32,452 | 97.4 | 61,658 | 185 | 66,552 | 200 | 15/16 |
| 3/4 | 49,781 | 178 | 94,584 | 338 | 102,091 | 364 | 1-1/8 |
| 7/8 | 67,157 | 279 | 127,599 | 530 | 137,725 | 572 | 1-5/16 |
| 1 | 88,221 | 418 | 167,620 | 795 | 180,923 | 858 | 1-1/2 |
| 1-1/8 | 111,007 | 593 | 210,913 | 1,126 | 227,652 | 1,216 | 1-11/16 |
| 1-1/4 | 142,135 | 837 | 270,091 | 1,591 | 291,527 | 1,717 | 1-7/8 |
| 1-3/8 | 168,641 | 1,096 | 320,417 | 2,083 | 345,847 | 2,248 | 2-1/16 |
| 1-1/2 | 206,578 | 1,456 | 392,498 | 2,767 | 423,648 | 2,987 | 2-1/4 |
Swipe the table sideways to see all columns.
Material grades (BS 1768 & BS 1083): Grade P: UTS 35 tonf/in² (yield 21) · Grade S: UTS 50 tonf/in² (yield 40) · Grade T: UTS 55 tonf/in² (yield 41)
To choose a torque wrench for these values, see suitable torque wrenches below.
UNF threads (Unified National Fine)
Load in newtons (N) and tightening torque in newton metres (N·m) for Grades P, S and T. A/F = across flats.
| Size (in) | Grade P | Grade S | Grade T | A/F (in) | |||
|---|---|---|---|---|---|---|---|
| Load (N) | Torque (N·m) | Load (N) | Torque (N·m) | Load (N) | Torque (N·m) | ||
| 1/4 | 5,232 | 6.28 | 9,941 | 11.9 | 10,730 | 12.9 | 7/16 |
| 5/16 | 8,410 | 12.5 | 15,979 | 23.8 | 17,247 | 25.7 | 1/2 |
| 3/8 | 12,911 | 22.7 | 24,531 | 43.2 | 26,478 | 46.6 | 9/16 |
| 7/16 | 17,416 | 35.9 | 33,091 | 68.2 | 35,717 | 73.6 | 5/8 |
| 1/2 | 23,685 | 55.4 | 45,002 | 105 | 48,574 | 114 | 3/4 |
| 9/16 | 30,075 | 79.0 | 57,143 | 150 | 61,678 | 162 | 13/16 |
| 5/8 | 38,156 | 111 | 72,496 | 210 | 78,250 | 227 | 15/16 |
| 3/4 | 56,078 | 195 | 106,549 | 370 | 115,005 | 399 | 1-1/8 |
| 7/8 | 76,297 | 309 | 144,965 | 587 | 156,470 | 634 | 1-5/16 |
| 1 | 99,200 | 459 | 188,480 | 873 | 203,439 | 942 | 1-1/2 |
| 1-1/8 | 128,738 | 667 | 244,602 | 1,267 | 264,015 | 1,368 | 1-11/16 |
| 1-1/4 | 161,358 | 925 | 306,580 | 1,757 | 330,911 | 1,896 | 1-7/8 |
| 1-3/8 | 199,331 | 1,252 | 378,728 | 2,378 | 408,786 | 2,567 | 2-1/16 |
| 1-1/2 | 240,377 | 1,642 | 456,717 | 3,119 | 492,965 | 3,367 | 2-1/4 |
Swipe the table sideways to see all columns.
Material grades (BS 1768 & BS 1083): Grade P: UTS 35 tonf/in² (yield 21) · Grade S: UTS 50 tonf/in² (yield 40) · Grade T: UTS 55 tonf/in² (yield 41)
To choose a torque wrench for these values, see suitable torque wrenches below.
Surface condition correction factors
Multiply the recommended torque by the factor below if the lubrication or finish differs from the stated conditions. Rows give the bolt finish; columns give the nut finish.
| Bolt finish ↓ / Nut finish → | Self & Oil | Zinc | Cadmium | Phosphate |
|---|---|---|---|---|
| Self | 1.00 | 1.00 | 0.80 | 0.90 |
| Zinc | 1.15 | 1.20 | 1.35 | 1.15 |
| Cadmium | 0.85 | 0.90 | 1.20 | 1.00 |
| Phosphate | 0.70 | 0.65 | 0.70 | 0.75 |
| Zinc w/ Wax | 0.60 | 0.55 | 0.65 | 0.55 |
Engineering formulae
Imperial
M = (P × D) / 60
M = torque (lb·ft), P = load (lb), D = diameter (in)
Metric
M = (P × D) / 5,000
M = torque (N·m), P = load (N), D = diameter (mm)
Suitable torque wrenches
Select a Torque Master torque wrench whose adjustable range includes the required torque. Ranges are taken from the 2026 catalogue; standard models are also available in ratchet type (R suffix) with the same ranges. To list every model that covers a specific value, use the Torque Wrench Selector.
| Required torque | Torque Master models (range) | Product family |
|---|---|---|
| Up to 6 N·m | Torque screwdrivers | |
| 2 to 35 N·m | Click type micrometer, Standard | |
| 10 to 340 N·m | Standard, Click type micrometer, Light weight | |
| 80 to 1,020 N·m | Standard, Light weight | |
| 540 to 4,050 N·m | Standard | |
| Above 4,050 N·m |
| Torque multipliers |
For torque above 4,050 N·m, a torque multiplier is used together with a torque wrench; the recommended torque wrench for each multiplier is listed on the torque multipliers page. View the full torque wrench range.