Read this before you use a number. These are calculated reference values, not a procedure. Where a joint has an engineered torque or bolt stress, from the equipment manufacturer, a flange design or your site's bolting procedure, that value governs. Torque only sets bolt load as well as the nut factor is known, so results in the field commonly scatter ±25% or more. Use calibrated tools and verify critical joints.
How the values are calculated
Every value uses the short-form torque equation:
T = K × D × F
where T is torque, K is the nut factor, D is the nominal bolt diameter and F is the target preload. For inch bolts, T in ft-lb is K × D(in) × F(lbf) ÷ 12. For metric bolts, T in N·m is K × D(m) × F(N).
Preload is a percentage of the bolt's strength times its tensile stress area:
- Tensile stress area, inch: As = 0.7854 × (D − 0.9743 ÷ n)², with n in threads per inch (ASME B1.1).
- Tensile stress area, metric: As = π/4 × (d − 0.9382 × P)², with P the thread pitch in mm (ISO 898-1).
- B7 studs: preload at 50% of specified minimum yield (ASTM A193): 105 ksi through 2-1/2 in., 95 ksi above 2-1/2 in. through 4 in. Studs 1 in. and smaller use UNC threads. Larger studs use the 8-thread series (8UN), which is standard for flange bolting.
- SAE Grade 5 and 8, metric 8.8 and 10.9: clamp load at 75% of proof load, the usual target for reusable structural and machinery bolts. Proof stress per SAE J429: Grade 5 is 85 ksi through 1 in. and 74 ksi from 1-1/8 to 1-1/2 in. Grade 8 is 120 ksi. Per ISO 898-1, class 8.8 is 580 MPa through M16 and 600 MPa above, and class 10.9 is 830 MPa.
Torque is rounded to the nearest 1 ft-lb below 100, the nearest 5 below 1,000 and the nearest 10 above that. Any finer precision would be false: the nut factor alone is rarely known better than ±10%.
ASTM A193 B7 stud bolt torque chart
B7 is the default stud for process piping and pressure equipment flanges: chromium-molybdenum alloy steel, quenched and tempered, usually paired with A194 2H heavy hex nuts. The 50% of yield preload used here sits in the middle of the range commonly used for gasketed joints. It is a reference point, not a recommendation for a specific flange.
| Stud dia. (in) | Threads / in | Stress area (in²) | Min. yield (ksi) | Preload at 50% yield (lbf) | Torque ft-lb K = 0.20 | Torque ft-lb K = 0.16 | Torque ft-lb K = 0.12 |
|---|---|---|---|---|---|---|---|
| 1/2 | 13 UNC | 0.142 | 105 | 7,450 | 62 | 50 | 37 |
| 5/8 | 11 UNC | 0.226 | 105 | 11,870 | 125 | 99 | 74 |
| 3/4 | 10 UNC | 0.334 | 105 | 17,560 | 220 | 175 | 130 |
| 7/8 | 9 UNC | 0.462 | 105 | 24,240 | 355 | 285 | 210 |
| 1 | 8 UNC | 0.606 | 105 | 31,800 | 530 | 425 | 320 |
| 1-1/8 | 8 UN | 0.790 | 105 | 41,500 | 780 | 620 | 465 |
| 1-1/4 | 8 UN | 1.000 | 105 | 52,480 | 1,090 | 875 | 655 |
| 1-3/8 | 8 UN | 1.234 | 105 | 64,760 | 1,480 | 1,190 | 890 |
| 1-1/2 | 8 UN | 1.492 | 105 | 78,320 | 1,960 | 1,570 | 1,170 |
| 1-5/8 | 8 UN | 1.775 | 105 | 93,170 | 2,520 | 2,020 | 1,510 |
| 1-3/4 | 8 UN | 2.082 | 105 | 109,310 | 3,190 | 2,550 | 1,910 |
| 1-7/8 | 8 UN | 2.414 | 105 | 126,740 | 3,960 | 3,170 | 2,380 |
| 2 | 8 UN | 2.771 | 105 | 145,460 | 4,850 | 3,880 | 2,910 |
| 2-1/4 | 8 UN | 3.557 | 105 | 186,760 | 7,000 | 5,600 | 4,200 |
| 2-1/2 | 8 UN | 4.442 | 105 | 233,210 | 9,720 | 7,770 | 5,830 |
| 2-3/4 | 8 UN | 5.425 | 95 | 257,690 | 11,810 | 9,450 | 7,090 |
| 3 | 8 UN | 6.506 | 95 | 309,050 | 15,450 | 12,360 | 9,270 |
| 3-1/4 | 8 UN | 7.686 | 95 | 365,070 | 19,770 | 15,820 | 11,860 |
| 3-1/2 | 8 UN | 8.963 | 95 | 425,750 | 24,840 | 19,870 | 14,900 |
| 3-3/4 | 8 UN | 10.339 | 95 | 491,100 | 30,690 | 24,560 | 18,420 |
| 4 | 8 UN | 11.813 | 95 | 561,110 | 37,410 | 29,930 | 22,440 |
Preload = 0.50 × minimum yield × tensile stress area. K = 0.20: clean as-received threads with light oil. K = 0.16: typical of nickel- or copper-based anti-seize. K = 0.12: typical of molybdenum disulfide pastes. Your lubricant's published K value should replace these.
SAE Grade 5 bolt torque chart
Grade 5 is medium-carbon steel, quenched and tempered. It's the most common general-purpose bolt in plants and on equipment, identified by three radial lines on the head.
| Bolt dia. (in) | Threads / in (UNC) | Stress area (in²) | Proof load stress (ksi) | Clamp load at 75% proof (lbf) | Torque ft-lb dry K = 0.20 | Torque ft-lb lubricated K = 0.15 |
|---|---|---|---|---|---|---|
| 1/4 | 20 | 0.0318 | 85 | 2,030 | 8 | 6 |
| 5/16 | 18 | 0.0524 | 85 | 3,340 | 17 | 13 |
| 3/8 | 16 | 0.0775 | 85 | 4,940 | 31 | 23 |
| 7/16 | 14 | 0.1063 | 85 | 6,780 | 49 | 37 |
| 1/2 | 13 | 0.1419 | 85 | 9,050 | 75 | 57 |
| 9/16 | 12 | 0.1819 | 85 | 11,600 | 110 | 82 |
| 5/8 | 11 | 0.2260 | 85 | 14,410 | 150 | 115 |
| 3/4 | 10 | 0.3345 | 85 | 21,320 | 265 | 200 |
| 7/8 | 9 | 0.4617 | 85 | 29,440 | 430 | 320 |
| 1 | 8 | 0.6057 | 85 | 38,620 | 645 | 485 |
| 1-1/8 | 7 | 0.7633 | 74 | 42,360 | 795 | 595 |
| 1-1/4 | 7 | 0.9691 | 74 | 53,790 | 1,120 | 840 |
| 1-3/8 | 6 | 1.1549 | 74 | 64,100 | 1,470 | 1,100 |
| 1-1/2 | 6 | 1.4053 | 74 | 77,990 | 1,950 | 1,460 |
Clamp load = 0.75 × proof load stress × tensile stress area. Coarse threads (UNC).
SAE Grade 8 bolt torque chart
Grade 8 is medium-carbon alloy steel, quenched and tempered, identified by six radial lines on the head. It's used where higher clamp load is needed in the same diameter.
| Bolt dia. (in) | Threads / in (UNC) | Stress area (in²) | Proof load stress (ksi) | Clamp load at 75% proof (lbf) | Torque ft-lb dry K = 0.20 | Torque ft-lb lubricated K = 0.15 |
|---|---|---|---|---|---|---|
| 1/4 | 20 | 0.0318 | 120 | 2,860 | 12 | 9 |
| 5/16 | 18 | 0.0524 | 120 | 4,720 | 25 | 18 |
| 3/8 | 16 | 0.0775 | 120 | 6,970 | 44 | 33 |
| 7/16 | 14 | 0.1063 | 120 | 9,570 | 70 | 52 |
| 1/2 | 13 | 0.1419 | 120 | 12,770 | 105 | 80 |
| 9/16 | 12 | 0.1819 | 120 | 16,370 | 155 | 115 |
| 5/8 | 11 | 0.2260 | 120 | 20,340 | 210 | 160 |
| 3/4 | 10 | 0.3345 | 120 | 30,100 | 375 | 280 |
| 7/8 | 9 | 0.4617 | 120 | 41,560 | 605 | 455 |
| 1 | 8 | 0.6057 | 120 | 54,520 | 910 | 680 |
| 1-1/8 | 7 | 0.7633 | 120 | 68,690 | 1,290 | 965 |
| 1-1/4 | 7 | 0.9691 | 120 | 87,220 | 1,820 | 1,360 |
| 1-3/8 | 6 | 1.1549 | 120 | 103,940 | 2,380 | 1,790 |
| 1-1/2 | 6 | 1.4053 | 120 | 126,470 | 3,160 | 2,370 |
Clamp load = 0.75 × 120 ksi proof load stress × tensile stress area. Coarse threads (UNC).
Metric bolt torque chart: class 8.8 and 10.9
Property class 8.8
| Size × pitch (mm) | Stress area (mm²) | Proof stress (MPa) | Clamp load at 75% proof (kN) | Torque N·m dry K = 0.20 | Torque N·m lubricated K = 0.15 |
|---|---|---|---|---|---|
| M10 × 1.5 | 58.0 | 580 | 25.2 | 50 | 38 |
| M12 × 1.75 | 84.3 | 580 | 36.7 | 88 | 66 |
| M16 × 2.0 | 156.7 | 580 | 68.2 | 220 | 165 |
| M20 × 2.5 | 244.8 | 600 | 110.2 | 440 | 330 |
| M24 × 3.0 | 352.5 | 600 | 158.6 | 760 | 570 |
| M30 × 3.5 | 560.6 | 600 | 252.3 | 1,510 | 1,140 |
| M36 × 4.0 | 816.7 | 600 | 367.5 | 2,650 | 1,980 |
| M42 × 4.5 | 1120.9 | 600 | 504.4 | 4,240 | 3,180 |
| M48 × 5.0 | 1473.1 | 600 | 662.9 | 6,360 | 4,770 |
Property class 10.9
| Size × pitch (mm) | Stress area (mm²) | Proof stress (MPa) | Clamp load at 75% proof (kN) | Torque N·m dry K = 0.20 | Torque N·m lubricated K = 0.15 |
|---|---|---|---|---|---|
| M10 × 1.5 | 58.0 | 830 | 36.1 | 72 | 54 |
| M12 × 1.75 | 84.3 | 830 | 52.5 | 125 | 94 |
| M16 × 2.0 | 156.7 | 830 | 97.5 | 310 | 235 |
| M20 × 2.5 | 244.8 | 830 | 152.4 | 610 | 455 |
| M24 × 3.0 | 352.5 | 830 | 219.4 | 1,050 | 790 |
| M30 × 3.5 | 560.6 | 830 | 349.0 | 2,090 | 1,570 |
| M36 × 4.0 | 816.7 | 830 | 508.4 | 3,660 | 2,750 |
| M42 × 4.5 | 1120.9 | 830 | 697.8 | 5,860 | 4,400 |
| M48 × 5.0 | 1473.1 | 830 | 917.0 | 8,800 | 6,600 |
Clamp load = 0.75 × proof stress × tensile stress area. Coarse pitch. For fine-pitch threads, recalculate the stress area with the torque calculator.
Using the chart without getting burned
Match the lubricant to the column
This is the most common mistake we see. A procedure written for moly paste gets run on dry studs, and the joint comes up around 40% short on load. Or a dry-thread torque gets put on studs slathered in anti-seize, and the studs go past yield. Write the lubricant on the procedure next to the torque value, and treat the two as one instruction.
The chart sets torque, not load
Roughly 90% of the torque you apply is spent overcoming friction under the nut and in the threads. Only about 10% stretches the bolt. Small changes in friction cause large changes in preload, which is why the nut factor deserves its own page. When load really matters, measure it: with a tensioner, ultrasonic elongation or load-monitoring fasteners.
Flanges have their own rules
A gasketed flange needs enough bolt load to seat and hold the gasket without crushing it or yielding the flange. That target comes from the flange and gasket, not from the bolt alone. The assembly needs a cross pattern and several passes. See flange bolt tightening sequence.
Large studs often belong on a tensioner
At 2 in. and up, torques climb into the thousands of foot-pounds and friction scatter gets more expensive. Above roughly 3 in., and anywhere preload uniformity matters, hydraulic tensioning is often the better method.
Hydraulic wrenches need a pressure, not a torque
On a hydraulic torque wrench, you set torque by setting pump pressure from that tool model's pressure-to-torque chart. Use the chart for the exact tool, and check that the gauge is calibrated. More in our hydraulic torque wrench guide.
Frequently asked questions
What torque should I use on a 1 inch B7 stud?
At a preload of 50% of the 105 ksi minimum yield (about 31,800 lbf), a 1"-8 UNC B7 stud needs roughly 530 ft-lb with a nut factor of 0.20, 425 ft-lb at 0.16, or 320 ft-lb at 0.12. Which one is right depends on the lubricant you actually use. For a gasketed flange, the joint's engineered target bolt stress governs, not a generic chart.
Why are there several torque columns for the same bolt?
Because torque does not set bolt load on its own. The same preload takes very different torque depending on the lubricant and surface condition, which the nut factor K captures. Pick the column that matches the lubricant on the job, or better, use the K value the lubricant manufacturer publishes.
Are these torque values for dry or lubricated bolts?
Both are shown. K = 0.20 is the usual assumption for clean, as-received steel threads with light oil. Lower K values represent lubricated or anti-seize conditions. Never use a lubricated torque value on a dry bolt or the reverse: dry threads at a lubricated torque are under-loaded, and lubricated threads at a dry torque can be loaded past yield.
Do these values apply to flange bolting?
They are a starting point, not a flange procedure. Gasketed flange joints are assembled to a target bolt stress chosen for the gasket, flange and bolt, with a tightening pattern and multiple passes. See our flange tightening sequence guide and ASME PCC-1.