M12 bolt torque specifications (8.8, 10.9, 12.9)
An M12 x 1.75 class 8.8 bolt takes 65 ft-lb (88 N·m) dry, and class 10.9 takes 93 ft-lb (126 N·m). Both are for plain steel, dry threads (K 0.20) tightened to a clamp load of 75% of proof load.
Contents13 sections
Key takeaways
Quick facts
| Coarse thread | M12 x 1.75 (84.3 mm²) |
|---|---|
| Fine thread | M12 x 1.25 (92.1 mm²) |
| Wrench, ISO 4014/4017 | 18 mm |
| Wrench, DIN 931/933 | 19 mm |
M12 bolt specifications
| Thread | Pitch | Tensile stress area |
|---|---|---|
| M12 x 1.75 (coarse) | 1.75 mm pitch | 84.3 mm² |
| M12 x 1.25 (fine) | 1.25 mm pitch | 92.1 mm² |
| Wrench, ISO 4014/4017 | 18 mm1 | |
| Wrench, older DIN 931/933 | 19 mm | |
Stress areas from ISO 898-1 Table 43.
M12 torque by grade
| Grade | Plain, dry K 0.201 | Lubricated K 0.151 | Clamp load |
|---|---|---|---|
| Class 4.6 | 25 ft-lb34 N·m | 19 ft-lb26 N·m | 14.2 kN |
| Class 8.8 | 65 ft-lb88 N·m | 49 ft-lb66 N·m | 36.7 kN |
| Class 10.9 | 93 ft-lb126 N·m | 70 ft-lb94 N·m | 52.5 kN |
| Class 12.9 | 109 ft-lb147 N·m | 81 ft-lb110 N·m | 61.3 kN |
Calculated with T = K × D × F, where F is 75% of the bolt’s proof load1 and K is the nut factor for each condition. Real preload from a torque wrench scatters by about ±25%4. When the equipment maker gives a torque, use theirs. How these numbers are made.
M12 4.6 torque
Proof 225 MPa · yield 240 MPa · tensile 400 MPa3. Clamp load at 75% of proof: 14.2 kN (M12 x 1.75).
| Condition | K | M12 x 1.75 | M12 x 1.25 |
|---|---|---|---|
| Plain steel, dryAs-received black or plain finish, clean threads, no lubricant | 0.201 | 25 ft-lb34 N·m | 28 ft-lb37 N·m |
| Zinc-plated, dryClean zinc-plated threads, no added lubricant | 0.181 | 23 ft-lb31 N·m | 25 ft-lb34 N·m |
| Lubricated (oil or grease)Light oil or grease on the threads and under the nut or head | 0.151 | 19 ft-lb26 N·m | 21 ft-lb28 N·m |
| Copper or metal-free anti-seizeLoctite C5-A copper or N-7000 metal-free anti-seize | 0.165 | 20 ft-lb27 N·m | 22 ft-lb30 N·m |
| Moly pasteMolybdenum disulfide paste | 0.116 | 14 ft-lb19 N·m | 15 ft-lb21 N·m |
M12 8.8 torque
Proof 580 MPa · yield 640 MPa · tensile 800 MPa3. Clamp load at 75% of proof: 36.7 kN (M12 x 1.75).
| Condition | K | M12 x 1.75 | M12 x 1.25 |
|---|---|---|---|
| Plain steel, dryAs-received black or plain finish, clean threads, no lubricant | 0.201 | 65 ft-lb88 N·m | 71 ft-lb96 N·m |
| Zinc-plated, dryClean zinc-plated threads, no added lubricant | 0.181 | 58 ft-lb79 N·m | 64 ft-lb87 N·m |
| Lubricated (oil or grease)Light oil or grease on the threads and under the nut or head | 0.151 | 49 ft-lb66 N·m | 53 ft-lb72 N·m |
| Copper or metal-free anti-seizeLoctite C5-A copper or N-7000 metal-free anti-seize | 0.165 | 52 ft-lb70 N·m | 57 ft-lb77 N·m |
| Moly pasteMolybdenum disulfide paste | 0.116 | 36 ft-lb48 N·m | 39 ft-lb53 N·m |
M12 10.9 torque
Proof 830 MPa · yield 940 MPa · tensile 1040 MPa3. Clamp load at 75% of proof: 52.5 kN (M12 x 1.75).
| Condition | K | M12 x 1.75 | M12 x 1.25 |
|---|---|---|---|
| Plain steel, dryAs-received black or plain finish, clean threads, no lubricant | 0.201 | 93 ft-lb126 N·m | 101 ft-lb138 N·m |
| Zinc-plated, dryClean zinc-plated threads, no added lubricant | 0.181 | 84 ft-lb113 N·m | 91 ft-lb124 N·m |
| Lubricated (oil or grease)Light oil or grease on the threads and under the nut or head | 0.151 | 70 ft-lb94 N·m | 76 ft-lb103 N·m |
| Copper or metal-free anti-seizeLoctite C5-A copper or N-7000 metal-free anti-seize | 0.165 | 74 ft-lb101 N·m | 81 ft-lb110 N·m |
| Moly pasteMolybdenum disulfide paste | 0.116 | 51 ft-lb69 N·m | 56 ft-lb76 N·m |
M12 12.9 torque
Proof 970 MPa · yield 1100 MPa · tensile 1220 MPa3. Clamp load at 75% of proof: 61.3 kN (M12 x 1.75).
| Condition | K | M12 x 1.75 | M12 x 1.25 |
|---|---|---|---|
| Plain steel, dryAs-received black or plain finish, clean threads, no lubricant | 0.201 | 109 ft-lb147 N·m | 119 ft-lb161 N·m |
| Zinc-plated, dryClean zinc-plated threads, no added lubricant | 0.181 | 98 ft-lb132 N·m | 107 ft-lb145 N·m |
| Lubricated (oil or grease)Light oil or grease on the threads and under the nut or head | 0.151 | 81 ft-lb110 N·m | 89 ft-lb121 N·m |
| Copper or metal-free anti-seizeLoctite C5-A copper or N-7000 metal-free anti-seize | 0.165 | 87 ft-lb118 N·m | 95 ft-lb129 N·m |
| Moly pasteMolybdenum disulfide paste | 0.116 | 60 ft-lb81 N·m | 65 ft-lb88 N·m |
Coarse or fine pitch
M12 x 1.75 coarse has 84.3 mm² of stress area 3; M12 x 1.25 fine has 92.1 mm² 1, about 9% more. In class 8.8 dry the fine thread takes 71 ft-lb instead of 65 ft-lb and clamps 40.1 kN instead of 36.7 kN. M12 also has a second fine pitch, M12 x 1.5, in the ISO 262 table 7. By the ISO stress-area formula it has about 88.1 mm², only 4.5% more than the coarse thread, so do not use the M12 x 1.25 column for it.
Wrench size: ISO or DIN
An ISO 4014/4017 M12 head is 18 mm across the flats; an older DIN 931/933 head is 19 mm 1. Nuts split the same way, with DIN 934 M12 nuts at 19 mm and ISO 4032 at 18 mm 1. A metric toolkit for M12 work therefore needs both an 18 mm and a 19 mm socket; the socket size chart lists the other sizes.
Proof load and the size steps
ISO 898-1 gives the M12 coarse proof load as 48,900 N in class 8.8 and 70,000 N in 10.9 3. The chart clamps at 75% of those: 36.7 kN (about 8,240 lbf) and 52.5 kN (about 11,800 lbf).
Class 8.8 dry runs 37 ft-lb at M10, 65 ft-lb at M12 and 103 ft-lb at M14. Next to 1/2 in (12.7 mm), M12 is the smaller bolt: on the same basis an M12 class 8.8 takes about 14% less torque than a 1/2-13 Grade 5 and clamps about 9% less.
Which class you have
The property class and the maker’s mark are on the head 3; see the bolt grades page. At M12, class 10.9 is 93 ft-lb and 12.9 is 109 ft-lb (147 N·m) dry.
When the chart does not apply
- Wheel studs. The Ford Escape uses M12 x 1.5 wheel nuts at 100 lb-ft (135 N·m), and Ford states the figure is for threads free of dirt and rust 2. Use the vehicle’s lug nut torque.
- Spark plugs. NGK gives 10.8 to 14.5 ft-lb for a flat-seat 12 mm plug in an aluminum head 8; see spark plug torque.
- Structural bolting. ISO 898-1 notes that for structural bolting the class 8.8 values for sizes over 16 mm apply from M12 3; see structural bolts.
Sources
- 1
- 2
- 3
- 4
- 5
- 6Henkel Corporation (LOCTITE), LOCTITE LB 8012 Moly Paste TDS, April 2015Checked 21 Oct 2026
- 7Wikipedia, Wikipedia: ISO metric screw thread (ISO 262 selected sizes table)Checked 21 Oct 2026
- 8NGK Spark Plugs (Niterra), How do I install spark plugs correctly?Checked 21 Oct 2026
Spotted a value that doesn’t match its source? Report an error
Related
- M10M10 x 1.5 bolt torque: 37 ft-lb (50 N·m) for class 8.8 and 53 ft-lb (72 N·m) for 10.9 dry, plus 12.9, M10 x 1.25 fine and the 16 vs 17 mm wrench.
- M14M14 x 2 bolt torque: 103 ft-lb (140 N·m) for class 8.8 and 148 ft-lb (200 N·m) for 10.9 dry, plus 12.9, M14 x 1.5 fine and the 21 vs 22 mm wrench.
- 1/2 in1/2-13 Grade 5 bolt torque is 75 ft-lb dry and Grade 8 is 107 ft-lb. Charts for 1/2-13 and 1/2-20 in Grade 2, 5 and 8, dry, zinc-plated and oiled.
- Class 8.8Class 8.8 bolt torque from M3 to M30, dry, zinc-plated and lubricated, with the ISO 898-1 proof stress step from 580 MPa to 600 MPa above M16.
- Class 10.9Class 10.9 bolt torque from M3 to M30, dry, zinc-plated and lubricated, with ISO 898-1 strength (830 MPa proof) and how it compares with 8.8 and 12.9.
- Class 12.9Class 12.9 bolt torque from M3 to M30, dry, zinc-plated and lubricated, with ISO 898-1 strength (970 MPa proof, 1,220 MPa tensile) and nut matching notes.
- Bolt torque calculatorBolt torque calculator for SAE and metric bolts by size, thread, grade and lubrication, using T = K × D × F with the proof loads from SAE J429 and ISO 898-1.
- Dry vs lubricated torqueWhy oiled bolts need less torque than dry ones for the same clamp load, with nut factor K values from Fastenal, NASA and Henkel for oil, zinc, anti-seize and moly.
- Ford EscapeFord Escape lug nut torque: 100 ft-lb (135 N·m) on M12 x 1.5 studs from 2007 through 2024, and the 84-114 ft-lb range in the 2004 guide, quoted from Ford.