Bolt Torque Calculator

Suggested Starting Values

The below estimated torque calculations are only offered as a guide. Use of its content by anyone is the sole responsibility of that person and they assume all risk. Due to many variables that affect the torque-tension relationship like human error, surface texture, and lubrication the only way to determine the correct torque is through experimentation under actual joint and assembly conditions.

ASTM A307

Bolt Size TPI Proof Load (lbs)1 Clamp Load (lbs)2 Tightening Torque (ft lbs)
Galv+Waxed Galv Plain
14 20 1,053 790 2 4 3
516 18 1,735 1,302 3 8 7
38 16 2,567 1,925 6 15 12
716 14 3,521 2,640 10 24 19
12 13 4,700 3,525 15 37 29
916 12 6,028 4,521 21 53 42
58 11 7,485 5,614 29 73 58
34 10 11,062 8,297 52 130 104
78 9 15,301 11,476 84 209 167
1 8 20,071 15,053 125 314 251
118 7 25,271 18,953 178 444 355
114 7 32,093 24,070 251 627 501
138 6 38,254 28,690 329 822 657
112 6 46,534 34,900 436 1,091 873
134 5 62,928 47,196 688 1,721 1,377
2 412 82,800 62,100 1,035 2,588 2,070
214 412 107,640 80,730 1,514 3,784 3,027
212 4 132,480 99,360 2,070 5,125 4,140
234 4 163,282 122,461 2,806 7,016 5,613
3 4 197,726 148,295 3,707 9,268 7,415
314 4 235,152 176,364 4,777 11,941 9,553
312 4 275,890 206,917 6,035 15,088 12,070
334 4 319,939 239,954 7,499 18,746 14,997
4 4 366,970 275,227 9,174 22,936 18,348
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SAE Grade 2

Bolt Size TPI Proof Load (lbs) 1 Clamp Load (lbs) 2 Tightening Torque (ft lbs)
Galv+Waxed Galv Plain
14 20 1,750 1,313 3 7 5
516 18 2,900 2,175 6 14 11
38 16 4,250 3,188 10 25 20
716 14 5,850 4,388 16 40 32
12 13 7,800 5,850 24 61 49
916 12 10,000 7,500 35 88 70
58 11 12,400 9,300 48 121 97
34 10 18,400 13,800 86 216 173
78 9 15,200 11,400 83 208 166
1 8 20,000 15,000 125 313 250
118 7 25,200 18,900 177 443 354
114 7 32,000 24,000 250 625 500
138 6 38,100 28,575 327 819 655
112 6 46,400 34,800 435 1,088 870
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ASTM A325

Bolt Size TPI Tension Tightening Torque Range (ft lbs) (Min - Max)
Min Max Galv+Waxed Plain
12 13 12,000 14,000 50 - 58 100 - 117
58 11 19,000 23,000 99 - 120 198 - 240
34 10 28,000 34,000 175 - 213 350 - 425
78 9 39,000 47,000 284 - 343 569 - 685
1 8 51,000 61,000 425 - 508 850 - 1,017
118 7 56,000 67,000 525 - 625 1,050 - 1,256
114 7 71,000 85,000 740 - 885 1,479 - 1,771
138 6 85,000 102,000 974 - 1,169 1,948 - 2,338
112 6 103,000 124,000 1,288 - 1,550 2,575 - 3,100
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ASTM A449 / SAE Grade 5*

Bolt Size TPI Proof Load (lbs) 1 Clamp Load (lbs) 2 Tightening Torque (ft lbs)
Galv+Waxed Galv Plain
14 20 2,700 2,025 4 11 8
516 18 4,450 3,338 9 22 17
38 16 6,600 4,950 15 39 31
716 14 9,050 6,788 25 62 49
12 13 12,050 9,038 38 94 75
916 12 15,450 11,588 54 136 109
58 11 19,200 14,400 75 188 150
34 10 28,400 21,300 133 333 266
78 9 39,250 29,438 215 537 429
1 8 51,500 38,625 322 805 644
118 7 56,450 42,338 397 992 794
114 7 71,700 53,775 560 1,400 1,120
138 6 85,450 64,088 734 1,836 1,469
112 6 104,000 78,000 975 2,438 1,950
134 5 104,500 78,375 1,143 2,857 2,286
2 412 137,500 103,125 1,719 4,297 3,438
214 412 178,750 134,063 2,514 6,284 5,027
212 4 220,000 165,000 3,438 8,594 6,875
234 4 271,150 203,363 4,660 11,651 9,321
3 4 328,350 246,263 6,157 15,391 12,313
* SAE J429 grade 5 bolts do not exceed 1-1/2" diameter.
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ASTM A193 B7 / ASTM A320 L7

Bolt Size TPI Proof Load (lbs) 1 Clamp Load (lbs) 2 Tightening Torque (ft lbs)
Galv+Waxed Galv Plain
14 20 3,350 2,513 5 13 10
516 18 5,500 4,125 11 27 21
38 16 8,150 6,113 19 48 38
716 14 11,150 8,363 30 76 61
12 13 14,900 11,175 47 116 93
916 12 19,100 14,325 67 168 134
58 11 23,750 17,813 93 232 186
34 10 35,050 26,288 164 411 329
78 9 48,500 36,375 265 663 530
1 8 63,650 47,738 398 995 796
118 7 80,100 60,075 563 1,408 1,126
118 8 82,934 62,201 583 1,458 1,166
114 7 101,750 76,313 795 1,987 1,590
114 8 105,006 78,754 820 2,051 1,641
138 6 121,300 90,975 1,042 2,606 2,085
138 8 129,492 97,119 1,113 2,782 2,226
112 6 147,550 110,663 1,383 3,458 2,767
112 8 156,687 117,515 1,469 3,672 2,938
134 5 199,500 149,625 2,182 5,455 4,364
134 8 218,400 163,800 - - 4,778
2 412 262,500 196,875 3,281 8,203 6,563
2 8 290,850 218,138 - - 7,271
214 412 341,250 255,938 4,799 11,997 9,598
214 8 373,801 280,351 - - 10,513
212 4 420,000 315,000 6,563 16,406 13,125
212 8 466,200 349,650 - - 14,569
234 4 468,500 351,263 8,050 20,124 16,100
234 8 515,851 386,888 - - 17,732
3 4 567,150 425,363 10,634 26,585 21,268
3 8 618,451 463,838 - - 23,192
314 4 674,500 505,875 13,701 34,252 27,402
314 8 730,550 547,913 - - 29,679
312 4 791,350 593,513 17,311 43,277 34,622
312 8 851,201 638,401 - - 37,240
334 4 917700 688275 21,509 53,771 43,017
334 8 982,300 736,725 - - 46,045
4 4 1052600 789450 26,315 65,788 52,630
4 8 1,121,950 841,463 - - 56,098
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ASTM A490

Bolt Size TPI Tension (lbs) Tightening Torque Range (ft lbs) (Min - Max)
Min Max Plain Lubricated
12 13 15,000 18,000 125 - 150 63 - 75
58 11 24,000 29,000 250 - 302 125 - 151
34 10 35,000 42,000 438 - 525 219 - 263
78 9 49,000 59,000 715 - 860 357 - 430
1 8 64,000 77,000 1,067 - 1,283 533 - 642
118 7 80,000 96,000 1,500 - 1,800 750 - 900
114 7 102,000 122,000 2,125 - 2,542 1,063 - 1,271
138 6 121,000 145,000 2,773 - 3,323 1,386 - 1,661
112 6 148,000 178,000 3,700 - 4,450 1,850 - 2,225
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ASTM A354-BD / SAE Grade 8*

Bolt Size TPI Proof Load (lbs) 1 Clamp Load (lbs) 2 Tightening Torque (ft lbs)
Plain Lubricated
14 20 3,800 2,850 12 6
516 18 6,300 4,725 25 12
38 16 9,300 6,975 44 22
716 14 12,750 9,563 70 35
12 13 17,050 12,788 107 53
916 12 21,850 16,388 154 77
58 11 27,100 20,325 212 106
34 10 40,100 30,075 376 188
78 9 55,450 41,588 606 303
1 8 72,700 54,525 909 454
118 7 91,550 68,663 1,287 644
114 7 120,000 90,000 1,875 938
138 6 138,600 103,950 2,382 1,191
112 6 168,600 126,450 3,161 1,581
134 5 228,000 171,000 4,988 2,494
2 412 300,000 225,000 7,500 3,750
214 412 390,000 292,500 10,969 5,484
212 4 480,000 360,000 15,000 7,500
234 4 517,650 388,238 17,794 8,897
3 4 626,850 470,138 23,507 11,753
314 4 745,500 559,125 30,286 15,143
312 4 874,650 655,988 38,266 19,133
334 4 1,014,300 760,725 47,545 23,773
4 4 1,163,400 872,550 58,100 29,085
* SAE J429 grade 8 bolts do not exceed 1-1/2″ diameter.
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