
The following tables of tightening torques for various strengths of bolt are provided as a general guide.
Care should be taken when using them because plating
finishes can act as a lubricant resulting in lower torque values corresponding with higher tensile values. Thus a lower torque value could result in a higher than
expected tensile load which in some cases could be greater than the ultimate tensile strength of the fastener resulting in failure.
What must also be taken into
consideration is the variation in stress area between minimum and maximum rolling diameter - the smaller the fastener the more significant this becomes.
The
fastener should not therefore be tested by use of torque to failure and then computing the tensile load. Instead a direct axial tensile load to failure should
be applied. The tables represent maximum tightening torque values. You should always thoroughly test the products to ensure suitability for your particular application.
| Nominal Thread Diameter mm |
4:6 Quality |
4:8 Quality |
5:6 Quality |
|||
| Course | Fine | Course | Fine | Course | Fine | |
| Nm | Nm | Nm | Nm | Nm | Nm | |
| M3 | 0.57 | 0.76 | 0.71 | |||
| M4 | 1.3 | 1.8 | 1.7 | |||
| M5 | 2.7 | 3.6 | 3.3 | |||
| M6 | 4.5 | 6.0 | 5.7 | |||
| M7 | 7.6 | 10.2 | 9.5 | |||
| M8 | 11.0 | 11.8 | 14.0 | 15.7 | 13.8 | 14.8 |
| M10 | 21.8 | 23.0 | 29.0 | 30.7 | 27.3 | 28.8 |
| M12 | 38.1 | 41.6 | 50.8 | 55.5 | 47.6 | 52.0 |
| M14 | 60.6 | 66.0 | 80.0 | 88.0 | 76.0 | 82.0 |
| M16 | 95.0 | 101.0 | 126.0 | 134.0 | 118.0 | 126.0 |
| M18 | 130.0 | 146.0 | 173.0 | 195.0 | 163.0 | 183.0 |
| M20 | 185.0 | 205.0 | 246.0 | 273.0 | 231.0 | 256.0 |
| Nominal Thread Diameter mm |
5:8 Quality |
6:6 Quality |
8:8 |
|||
| Course | Fine | Course | Fine | Course | Fine | |
| Nm | Nm | Nm | Nm | Nm | Nm | |
| M3 | 0.95 | 0.85 | 1.5 | |||
| M4 | 2.2 | 2.0 | 3.5 | |||
| M5 | 4.5 | 4.0 | 7.1 | |||
| M6 | 7.6 | 6.8 | 12.1 | |||
| M7 | 12.7 | 11.4 | 20.3 | |||
| M8 | 18.4 | 19.7 | 16.5 | 17.7 | 29.4 | 31.5 |
| M10 | 36.4 | 38.4 | 32.8 | 34.6 | 58.3 | 61.0 |
| M12 | 64.0 | 69.0 | 57.0 | 62.0 | 101.0 | 111.0 |
| M14 | 101.0 | 110.0 | 91.0 | 99.0 | 161.0 | 176.0 |
| M16 | 158.0 | 168.0 | 142.0 | 151.0 | 252.0 | 268.0 |
| M18 | 217.0 | 244.0 | 220.0 | 347.0 | 390.0 | |
| M20 | 308.0 | 342.0 | 492.0 | 546.0 | ||
| Nominal Thread Diameter mm |
9.8 Quality |
10:9 Quality |
12:9 Quality |
14:9 Quality |
||||
| Course | Fine | Course | Fine | Course | Fine | Course | Fine | |
| Nm | Nm | Nm | Nm | Nm | Nm | Nm | Nm | |
| M3 | 1.7 | 2.1 | 2.6 | 3.0 | ||||
| M4 | 4.0 | 5.0 | 6.0 | 7.0 | ||||
| M5 | 8.0 | 10.0 | 12.0 | 14.0 | ||||
| M6 | 13.6 | 13.0 | 17.0 | 18.0 | 20.4 | 22.0 | 23.8 | |
| M7 | 22.8 | 28.6 | 34.3 | 40.0 | ||||
| M8 | 33.1 | 35.4 | 41.3 | 44.3 | 49.6 | 53.2 | 57.9 | 62.0 |
| M10 | 66.0 | 69.0 | 82.0 | 86.0 | 98.0 | 104.0 | 115.0 | 121.0 |
| M12 | 114.0 | 125.0 | 143.0 | 156.0 | 171.0 | 187.0 | 200.0 | 219.0 |
| M14 | 182.0 | 198.0 | 227.0 | 247.0 | 273.0 | 297.0 | 318.0 | 346.0 |
| M16 | 284.0 | 302.0 | 355.0 | 377.0 | 426.0 | 453.0 | 497.0 | 528.0 |
| M18 | 391.0 | 439.0 | 488.0 | 549.0 | 586.0 | 659.0 | 683.0 | 769.0 |
| M20 | 554.0 | 615.0 | 693.0 | 768.0 | 830.0 | 922.0 | 969.0 | 1076.0 |
| Nominal Thread Diameter mm | 'A' Quality |
'P' Quality |
||||||
|
BSW |
BSF |
UNC |
UNF |
BSW |
BSF |
UNC |
UNF |
|
|
lbf ft |
lbf ft |
lbf ft |
lbf ft |
lbf ft |
lbf ft |
lbf ft |
lbf ft |
|
| 1/4 | 3.6 | 4.0 | 3.6 | 4.0 | 5.3 | 5.9 | 5.3 | 6.0 |
| 3/16 | 7.4 | 7.9 | 7.4 | 8.2 | 11.0 | 12.0 | 11.0 | 12.0 |
| 3/8 | 13.0 | 14.0 | 13.0 | 15.0 | 19.0 | 21.0 | 19.0 | 22.0 |
| 7/16 | 21.0 | 23.0 | 21.0 | 23.0 | 31.0 | 33.0 | 31.0 | 34.0 |
| 1/2 | 31.0 | 34.0 | 32.0 | 36.0 | 46.0 | 50.0 | 47.0 | 53.0 |
| 9/16 | 46.0 | 50.0 | 46.0 | 52.0 | 68.0 | 73.0 | 68.0 | 76.0 |
| 5/8 | 64.0 | 68.0 | 64.0 | 72.0 | 93.0 | 100.0 | 94.0 | 108.0 |
| 3/4 | 113.0 | 118.0 | 114.0 | 126.0 | 166.0 | 173.0 | 167.0 | 185.0 |
| Nominal Thread Diameter mm | 'R' Quality |
'S' Quality |
||||||
|
BSW |
BSF |
UNC |
UNF |
BSW |
BSF |
UNC |
UNF |
|
|
lbf
ft |
lbf
ft |
lbf
ft |
lbf
ft |
lbf
ft |
lbf
ft |
lbf
ft |
lbf
ft |
|
| 1/4 | 8.2 | 9.1 | 8.2 | 9.3 | 9.1 | 9.1 | 10.0 | 10.0 |
| 3/16 | 17.0 | 16.0 | 17.0 | 19.0 | 19.0 | 19.0 | 20.0 | 31.0 |
| 3/8 | 30.0 | 32.0 | 30.0 | 34.0 | 33.0 | 33.0 | 36.0 | 38.0 |
| 7/16 | 48.0 | 51.0 | 48.0 | 53.0 | 53.0 | 53.0 | 58.0 | 60.0 |
| 1/2 | 70.0 | 77.0 | 73.0 | 82.0 | 79.0 | 82.0 | 86.0 | 91.0 |
| 9/16 | 104.0 | 113.0 | 105.0 | 117.0 | 117.0 | 117.0 | 126.0 | 131.0 |
| 5/8 | 144.0 | 154.0 | 145.0 | 164.0 | 161.0 | 162.0 | 172.0 | 183.0 |
| 3/4 | 256.0 | 268.0 | 256.0 | 286.0 | 286.0 | 288.0 | 300.0 | 319.0 |
Nominal
Thread Diameter mm |
'T' Quality |
'X' Quality |
||||||
|
BSW |
BSF |
UNC |
UNF |
BSW |
BSF |
UNC |
UNF |
|
|
lbf
ft |
lbf
ft |
lbf
ft |
lbf
ft |
lbf
ft |
lbf
ft |
lbf
ft |
lbf
ft |
|
| 1/4 | 11.0 | 12.0 | 11.0 | 12.0 | 15.0 | 17.0 | 15.0 | 17.0 |
| 3/16 | 22.0 | 23.0 | 22.0 | 24.0 | 31.0 | 33.0 | 31.0 | 34.0 |
| 3/8 | 38.0 | 41.0 | 39.0 | 44.0 | 55.0 | 59.0 | 55.0 | 63.0 |
| 7/16 | 62.0 | 67.0 | 62.0 | 69.0 | 88.0 | 95.0 | 89.0 | 99.0 |
| 1/2 | 91.0 | 100.0 | 94.0 | 106.0 | 130.0 | 143.0 | 135.0 | 152.0 |
| 9/16 | 135.0 | 146.0 | 137.0 | 152.0 | 194.0 | 210.0 | 195.0 | 217.0 |
| 5/8 | 187.0 | 200.0 | 188.0 | 212.0 | 267.0 | 286.0 | 269.0 | 304.0 |
| 3/4 | 331.0 | 347.0 | 333.0 | 474.0 | 497.0 | 477.0 | 529.0 | |
| Nominal Thread Diameter mm | Quality |
|||||
|
'A' |
'P' |
'R' |
'S' |
'T' |
'X' |
|
|
lbf
in |
lbf
in |
lbf
in |
lbf
in |
lbf
in |
lbf
in |
|
| No. 2 | 1.8 | 2.7 | 4.1 | 4.6 | 5.3 | 7.6 |
| No. 3 | 2.8 | 4.1 | 6.3 | 7.0 | 8.1 | 11.6 |
| No. 4 | 3.9 | 5.7 | 8.9 | 9.9 | 11.5 | 16.4 |
| No. 5 | 5.5 | 8.1 | 12.5 | 14.0 | 16.2 | 23.1 |
| No. 6 | 7.5 | 11.0 | 17.0 | 19.0 | 22.0 | 31.5 |
| No. 8 | 12.9 | 18.9 | 29.2 | 32.6 | 37.8 | 54.0 |
| No. 10 | 20.3 | 29.8 | 46.1 | 51.9 | 85.4 | |
| No. 12 | 29.9 | 43.8 | 67.7 | 75.6 | 87.5 | 125.0 |
| Nominal Thread Diameter mm | Quality |
|||||
|
'A' |
'P' |
'R' |
'S' |
'T' |
'X' |
|
|
lbf
in |
lbf
in |
lbf
in |
lbf
in |
lbf
in |
lbf
in |
|
| 8 BA | 1.9 | 2.8 | 4.4 | 4.9 | 5.6 | 8.1 |
| 7 BA | 2.7 | 4.0 | 6.2 | 6.9 | 8.0 | 11.5 |
| 6 BA | 3.9 | 5.6 | 8.7 | 10.0 | 11.3 | 16.1 |
| 5 BA | 5.9 | 8.6 | 13.4 | 14.9 | 17.3 | 24.8 |
| 4 BA | 8.4 | 12.3 | 19.0 | 21.3 | 24.6 | 35.3 |
| 3 BA | 12.5 | 18.3 | 28.2 | 31.6 | 36.6 | 52.4 |
| 2 BA | 19.1 | 28.0 | 43.3 | 48.4 | 56.0 | 80.2 |
| 1 BA | 27.4 | 40.2 | 62.1 | 69.4 | 80.0 | 115.0 |
| 0 BA | 40.2 | 59.0 | 91.1 | 101.9 | 118.0 | 169.0 |