Torque-Tension Relationship for Metric Fasteners
Class 4.6
Class 8.8
Class 10.9
Class 12.9
Nominal
Dia.
Pitch
(mm)
Clamp
Tightening Torque
Clamp
Tightening Torque
C lamp
Tightening Torque
Clamp
Tightening Torque
Load
Lubricated Zinc Plated Plain&Dry
Load
Lubricated Zinc Plated Plain&Dry
Load
Lubricated Zinc Plated Plain&Dry
Load
Lubricated As-Received
Plain&Dry
(lbs)
(ft-lbs)
(ft-lbs)
(ft-lbs)
(lbs)
(ft-lbs)
(ft-lbs)
(ft-lbs)
(lbs)
(ft-lbs)
(ft-lbs)
(ft-lbs)
(lbs)
(ft-lbs)
(ft-lbs)
(ft-lbs)
4
0.7
333
0.7
0.7
0.9
858
1.7
1.9
2.3
1228
2.4
2.7
3.2
1436
2.8
3.2
3.8
5
0.8
538
1.3
1.5
1.8
1387
3.4
3.9
4.5
1985
4.9
5.5
6.5
2319
5.7
6.5
7.6
6
1
763
2.3
2.6
3.0
1968
5.8
6.6
7.7
2816
8.3
9.4
11.1
3291
9.7
11.0
13.0
7
1
1095
3.8
4.3
5.0
2822
9.7
11.0
13.0
4039
13.9
15.8
18.5
4720
16.3
18.4
21.7
8
1.25
1389
5.5
6.2
7.3
3580
14.1
16.0
18.8
5123
20.2
22.9
26.9
5987
23.6
26.7
31.4
10
1.5
2200
10.8
12.3
14.4
5671
27.9
31.6
37.2
8115
39.9
45.2
53.2
9484
46.7
52.9
62.2
12
1.75
3197
18.9
21.4
25.2
8240
48.7
55.1
64.9
11792
69.6
78.9
92.8
13781
81.4
92.2
108.5
14
2
4379
30.2
34.2
40.2
11289
77.8
88.1
103.7
16154
111.3
126.1
148.4
18879
130.0
147.4
173.4
16
2
5943
47
53
62
15320
121
137
161
21924
173
196
230
25622
202
229
269
18
2.5
7301
65
73
86
18822
167
189
222
26934
239
270
318
31477
279
316
372
20
2.5
9286
91
104
122
23938
236
267
314
34256
337
382
449
40034
394
446
525
22
2.5
11509
125
141
166
29669
321
364
428
42457
460
521
613
49619
537
609
716
24
3
13372
158
179
211
34471
407
461
543
49329
582
660
777
57649
681
771
908
27
3
17428
232
262
309
44924
597
676
796
64288
854
968
1139
75132
998
1131
1331
30
3.5
21266
314
356
419
54819
809
917
1079
78448
1158
1312
1544
91680
1353
1534
1804
33
3.5
26310
427
484
570
67821
1101
1248
1468
97055
1576
1786
2101
113425
1842
2087
2455
36
4
30982
549
622
732
79866
1415
1603
1886
114291
2024
2294
2699
133569
2366
2681
3154
The torque values can only be achieved if nut (or tapped hole) has a proof load greater than or equal to the bolt's minimum ultimate tensile strength.
Clamp loads estimated as 75% of proof load for specified bolts.
Torque values listed in foot-pounds .
Torque values calculated from formula T=KDF where; K=0.15 for "lubricated" condition, K=0.17 for zinc plated and dry condition (or as-received for the 12.9), K=0.20 for plain and dry
condition
Caution: All material included in this chart is advisory only, and its use by anyone is voluntary. In developing this information, Fastenal has made a determined effort
to present its contents accurately. Extreme caution should be used when using a formula for torque/tension relationships. Torque is only an indirect indication of
tension. Under/over tightening of fasteners can result in costly equipment failure or personal injury.
Rev 3-4-09