M5 bolt torque specifications (8.8, 10.9, 12.9)
An M5 x 0.8 class 8.8 bolt takes 55 in-lb (6.2 N·m) dry, and class 10.9 takes 78 in-lb (8.8 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
- Class 8.8 dry: 55 in-lb (6.2 N·m); class 10.9 dry: 78 in-lb (8.8 N·m).
- M5 x 0.5 fine has about 13% more stress area than M5 x 0.8, the largest fine-pitch gain of any size in this chart.
- With moly paste (K 0.11) the 8.8 torque falls to 30 in-lb, a little over half the dry value 1.
- Class 4.6 dry is only 21 in-lb (2.4 N·m), so check the head marking before using the 8.8 row.
Quick facts
| Coarse thread | M5 x 0.8 (14.2 mm²) |
|---|---|
| Fine thread | M5 x 0.5 (16.1 mm²) |
| Wrench, ISO 4014/4017 | 8 mm |
| Wrench, DIN 931/933 | 8 mm (same) |
M5 bolt specifications
| Thread | Pitch | Tensile stress area |
|---|---|---|
| M5 x 0.8 (coarse) | 0.8 mm pitch | 14.2 mm² |
| M5 x 0.5 (fine) | 0.5 mm pitch | 16.1 mm² |
| Wrench, ISO 4014/4017 | 8 mm2 | |
Stress areas from ISO 898-1 Table 43.
M5 torque by grade
| Grade | Plain, dry K 0.202 | Lubricated K 0.152 | Clamp load |
|---|---|---|---|
| Class 4.6 | 21 in-lb2.4 N·m | 16 in-lb1.8 N·m | 2.4 kN |
| Class 8.8 | 55 in-lb6.2 N·m | 41 in-lb4.6 N·m | 6.2 kN |
| Class 10.9 | 78 in-lb8.8 N·m | 59 in-lb6.6 N·m | 8.8 kN |
| Class 12.9 | 91 in-lb10 N·m | 69 in-lb7.7 N·m | 10.3 kN |
Calculated with T = K × D × F, where F is 75% of the bolt’s proof load2 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.
M5 4.6 torque
Proof 225 MPa · yield 240 MPa · tensile 400 MPa3. Clamp load at 75% of proof: 2.4 kN (M5 x 0.8).
| Condition | K | M5 x 0.8 | M5 x 0.5 |
|---|---|---|---|
| Plain steel, dryAs-received black or plain finish, clean threads, no lubricant | 0.202 | 21 in-lb2.4 N·m | 24 in-lb2.7 N·m |
| Zinc-plated, dryClean zinc-plated threads, no added lubricant | 0.182 | 19 in-lb2.2 N·m | 22 in-lb2.4 N·m |
| Lubricated (oil or grease)Light oil or grease on the threads and under the nut or head | 0.152 | 16 in-lb1.8 N·m | 18 in-lb2.0 N·m |
| Copper or metal-free anti-seizeLoctite C5-A copper or N-7000 metal-free anti-seize | 0.165 | 17 in-lb1.9 N·m | 19 in-lb2.2 N·m |
| Moly pasteMolybdenum disulfide paste | 0.111 | 12 in-lb1.3 N·m | 13 in-lb1.5 N·m |
M5 8.8 torque
Proof 580 MPa · yield 640 MPa · tensile 800 MPa3. Clamp load at 75% of proof: 6.2 kN (M5 x 0.8).
| Condition | K | M5 x 0.8 | M5 x 0.5 |
|---|---|---|---|
| Plain steel, dryAs-received black or plain finish, clean threads, no lubricant | 0.202 | 55 in-lb6.2 N·m | 62 in-lb7.0 N·m |
| Zinc-plated, dryClean zinc-plated threads, no added lubricant | 0.182 | 49 in-lb5.6 N·m | 56 in-lb6.3 N·m |
| Lubricated (oil or grease)Light oil or grease on the threads and under the nut or head | 0.152 | 41 in-lb4.6 N·m | 46 in-lb5.3 N·m |
| Copper or metal-free anti-seizeLoctite C5-A copper or N-7000 metal-free anti-seize | 0.165 | 44 in-lb4.9 N·m | 50 in-lb5.6 N·m |
| Moly pasteMolybdenum disulfide paste | 0.111 | 30 in-lb3.4 N·m | 34 in-lb3.9 N·m |
M5 10.9 torque
Proof 830 MPa · yield 940 MPa · tensile 1040 MPa3. Clamp load at 75% of proof: 8.8 kN (M5 x 0.8).
| Condition | K | M5 x 0.8 | M5 x 0.5 |
|---|---|---|---|
| Plain steel, dryAs-received black or plain finish, clean threads, no lubricant | 0.202 | 78 in-lb8.8 N·m | 89 in-lb10 N·m |
| Zinc-plated, dryClean zinc-plated threads, no added lubricant | 0.182 | 70 in-lb8.0 N·m | 80 in-lb9.0 N·m |
| Lubricated (oil or grease)Light oil or grease on the threads and under the nut or head | 0.152 | 59 in-lb6.6 N·m | 67 in-lb7.5 N·m |
| Copper or metal-free anti-seizeLoctite C5-A copper or N-7000 metal-free anti-seize | 0.165 | 63 in-lb7.1 N·m | 71 in-lb8.0 N·m |
| Moly pasteMolybdenum disulfide paste | 0.111 | 43 in-lb4.9 N·m | 49 in-lb5.5 N·m |
M5 12.9 torque
Proof 970 MPa · yield 1100 MPa · tensile 1220 MPa3. Clamp load at 75% of proof: 10.3 kN (M5 x 0.8).
| Condition | K | M5 x 0.8 | M5 x 0.5 |
|---|---|---|---|
| Plain steel, dryAs-received black or plain finish, clean threads, no lubricant | 0.202 | 91 in-lb10 N·m | 104 in-lb12 N·m |
| Zinc-plated, dryClean zinc-plated threads, no added lubricant | 0.182 | 82 in-lb9.3 N·m | 93 in-lb11 N·m |
| Lubricated (oil or grease)Light oil or grease on the threads and under the nut or head | 0.152 | 69 in-lb7.7 N·m | 78 in-lb8.8 N·m |
| Copper or metal-free anti-seizeLoctite C5-A copper or N-7000 metal-free anti-seize | 0.165 | 73 in-lb8.3 N·m | 83 in-lb9.4 N·m |
| Moly pasteMolybdenum disulfide paste | 0.111 | 50 in-lb5.7 N·m | 57 in-lb6.4 N·m |
Coarse or fine pitch
The tables are built on M5 x 0.8 coarse, stress area 14.2 mm² 3. The fine pitch, M5 x 0.5, is in the ISO 262 selected-sizes table 6; at 16.1 mm² it has about 13% more stress area. That is the biggest coarse-to-fine gain of the twelve sizes here, because a 0.3 mm pitch change is large next to a 5 mm diameter. In class 8.8 dry the fine thread takes 62 in-lb instead of 55 in-lb and clamps 7.0 kN instead of 6.2 kN.
Fitting the fine-thread figure to a coarse M5 would put about 13% more load on it than intended. Check the pitch before using the fine column.
The size between M4 and M6
Class 8.8 dry torque is 27 in-lb at M4, 55 in-lb at M5 and 93 in-lb at M6. The clamp load in 8.8 is 6.2 kN, about 1,390 lbf, and in 10.9 it is 8.8 kN, about 1,990 lbf.
Class 12.9 dry is 91 in-lb (10 N·m). Even class 10.9 dry, at 78 in-lb, is only 6.5 ft-lb, so every M5 value in the chart is given in in-lb.
Wrench size
An M5 hex head takes an 8 mm wrench in both ISO 4014/4017 and DIN 931/933 2.
Which class you have
The class is stamped on the head with the maker’s mark, as ISO 898-1 requires 3; the bolt grades page shows what to look for. Class 10.9 (830 MPa proof) and 12.9 (970 MPa proof) 3 give 78 and 91 in-lb dry. If the head reads 4.6, the dry torque is only 21 in-lb (2.4 N·m), less than 40% of the 8.8 figure.
When the chart does not apply
The torque you need depends heavily on what is on the threads. For class 8.8 M5:
- Plain, dry (K 0.20): 55 in-lb 2
- Oil or grease (K 0.15): 41 in-lb 2
- Moly paste (K 0.11): 30 in-lb 1
Using the dry 55 in-lb on a moly-coated M5 would give about 80% more clamp load than the 75% target, enough to go past proof load. Use the row that matches the threads, see dry vs lubricated torque, and follow the equipment maker’s torque where one is given.
Sources
- 1Henkel Corporation (LOCTITE), LOCTITE LB 8012 Moly Paste TDS, April 2015Checked 21 Oct 2026
- 2
- 3
- 4
- 5
- 6Wikipedia, Wikipedia: ISO metric screw thread (ISO 262 selected sizes table)Checked 21 Oct 2026
Spotted a value that doesn’t match its source? Report an error
Related
- M4M4 x 0.7 screw torque: 27 in-lb (3.1 N·m) for class 8.8 and 39 in-lb (4.4 N·m) for 10.9 dry, with 12.9, M4 x 0.5 fine, zinc and oiled values.
- M6M6 x 1 bolt torque: 93 in-lb (10 N·m) for class 8.8 and 11 ft-lb (15 N·m) for 10.9 dry, with 12.9, M6 x 0.75 fine, zinc, oiled and anti-seize.
- 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.
- 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.