M16 bolt torque specifications (8.8, 10.9, 12.9)
An M16 x 2 class 8.8 bolt takes 161 ft-lb (219 N·m) dry, and class 10.9 takes 231 ft-lb (313 N·m). Both are for plain steel, dry threads (K 0.20) tightened to a clamp load of 75% of proof load.
Contents14 sections
Key takeaways
- Class 8.8 dry: 161 ft-lb (219 N·m); class 10.9 dry: 231 ft-lb (313 N·m).
- M16 is the largest size on the lower class 8.8 proof stress of 580 MPa; from M20 up the chart uses 600 MPa 1.
- M16 x 1.5 fine carries about 6% more clamp load than M16 x 2.
- Going up to M20 roughly doubles the class 8.8 torque, to 325 ft-lb.
Quick facts
| Coarse thread | M16 x 2 (157 mm²) |
|---|---|
| Fine thread | M16 x 1.5 (167 mm²) |
| Wrench, ISO 4014/4017 | 24 mm |
| Wrench, DIN 931/933 | 24 mm (same) |
M16 bolt specifications
| Thread | Pitch | Tensile stress area |
|---|---|---|
| M16 x 2 (coarse) | 2 mm pitch | 157.0 mm² |
| M16 x 1.5 (fine) | 1.5 mm pitch | 167.0 mm² |
| Wrench, ISO 4014/4017 | 24 mm2 | |
Stress areas from ISO 898-1 Table 41.
M16 torque by grade
| Grade | Plain, dry K 0.202 | Lubricated K 0.152 | Clamp load |
|---|---|---|---|
| Class 4.6 | 63 ft-lb85 N·m | 47 ft-lb64 N·m | 26.5 kN |
| Class 8.8 | 161 ft-lb219 N·m | 121 ft-lb164 N·m | 68.3 kN |
| Class 10.9 | 231 ft-lb313 N·m | 173 ft-lb235 N·m | 97.7 kN |
| Class 12.9 | 270 ft-lb365 N·m | 202 ft-lb274 N·m | 114.2 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%3. When the equipment maker gives a torque, use theirs. How these numbers are made.
M16 4.6 torque
Proof 225 MPa · yield 240 MPa · tensile 400 MPa1. Clamp load at 75% of proof: 26.5 kN (M16 x 2).
| Condition | K | M16 x 2 | M16 x 1.5 |
|---|---|---|---|
| Plain steel, dryAs-received black or plain finish, clean threads, no lubricant | 0.202 | 63 ft-lb85 N·m | 67 ft-lb90 N·m |
| Zinc-plated, dryClean zinc-plated threads, no added lubricant | 0.182 | 56 ft-lb76 N·m | 60 ft-lb81 N·m |
| Lubricated (oil or grease)Light oil or grease on the threads and under the nut or head | 0.152 | 47 ft-lb64 N·m | 50 ft-lb68 N·m |
| Copper or metal-free anti-seizeLoctite C5-A copper or N-7000 metal-free anti-seize | 0.164 | 50 ft-lb68 N·m | 53 ft-lb72 N·m |
| Moly pasteMolybdenum disulfide paste | 0.115 | 34 ft-lb47 N·m | 37 ft-lb50 N·m |
M16 8.8 torque
Proof 580 MPa · yield 640 MPa · tensile 800 MPa1. Clamp load at 75% of proof: 68.3 kN (M16 x 2).
| Condition | K | M16 x 2 | M16 x 1.5 |
|---|---|---|---|
| Plain steel, dryAs-received black or plain finish, clean threads, no lubricant | 0.202 | 161 ft-lb219 N·m | 171 ft-lb232 N·m |
| Zinc-plated, dryClean zinc-plated threads, no added lubricant | 0.182 | 145 ft-lb197 N·m | 154 ft-lb209 N·m |
| Lubricated (oil or grease)Light oil or grease on the threads and under the nut or head | 0.152 | 121 ft-lb164 N·m | 129 ft-lb174 N·m |
| Copper or metal-free anti-seizeLoctite C5-A copper or N-7000 metal-free anti-seize | 0.164 | 129 ft-lb175 N·m | 137 ft-lb186 N·m |
| Moly pasteMolybdenum disulfide paste | 0.115 | 89 ft-lb120 N·m | 94 ft-lb128 N·m |
M16 10.9 torque
Proof 830 MPa · yield 940 MPa · tensile 1040 MPa1. Clamp load at 75% of proof: 97.7 kN (M16 x 2).
| Condition | K | M16 x 2 | M16 x 1.5 |
|---|---|---|---|
| Plain steel, dryAs-received black or plain finish, clean threads, no lubricant | 0.202 | 231 ft-lb313 N·m | 245 ft-lb333 N·m |
| Zinc-plated, dryClean zinc-plated threads, no added lubricant | 0.182 | 208 ft-lb281 N·m | 221 ft-lb299 N·m |
| Lubricated (oil or grease)Light oil or grease on the threads and under the nut or head | 0.152 | 173 ft-lb235 N·m | 184 ft-lb249 N·m |
| Copper or metal-free anti-seizeLoctite C5-A copper or N-7000 metal-free anti-seize | 0.164 | 185 ft-lb250 N·m | 196 ft-lb266 N·m |
| Moly pasteMolybdenum disulfide paste | 0.115 | 127 ft-lb172 N·m | 135 ft-lb183 N·m |
M16 12.9 torque
Proof 970 MPa · yield 1100 MPa · tensile 1220 MPa1. Clamp load at 75% of proof: 114.2 kN (M16 x 2).
| Condition | K | M16 x 2 | M16 x 1.5 |
|---|---|---|---|
| Plain steel, dryAs-received black or plain finish, clean threads, no lubricant | 0.202 | 270 ft-lb365 N·m | 287 ft-lb389 N·m |
| Zinc-plated, dryClean zinc-plated threads, no added lubricant | 0.182 | 243 ft-lb329 N·m | 258 ft-lb350 N·m |
| Lubricated (oil or grease)Light oil or grease on the threads and under the nut or head | 0.152 | 202 ft-lb274 N·m | 215 ft-lb292 N·m |
| Copper or metal-free anti-seizeLoctite C5-A copper or N-7000 metal-free anti-seize | 0.164 | 216 ft-lb292 N·m | 229 ft-lb311 N·m |
| Moly pasteMolybdenum disulfide paste | 0.115 | 148 ft-lb201 N·m | 158 ft-lb214 N·m |
Coarse or fine pitch
M16 x 2 coarse has 157 mm² of stress area 1; M16 x 1.5 fine has 167 mm² 2, about 6.4% more. In class 8.8 dry the fine thread takes 171 ft-lb instead of 161 ft-lb and clamps 72.6 kN instead of 68.3 kN. M16 and M14 share the same 2 mm coarse pitch, so the pitch alone will not tell the two apart; measure the diameter.
Class 8.8 above and below M16
ISO 898-1 gives class 8.8 a proof stress of 580 MPa for diameters up to 16 mm and 600 MPa above 16 mm, with minimum tensile strength rising from 800 to 830 MPa 1. M16 is the last size on the lower values. Its coarse proof load is listed as 91,000 N in 8.8 and 130,000 N in 10.9 1, and the chart clamps at 75% of those: 68.3 kN (about 15,350 lbf) and 97.7 kN (about 21,970 lbf).
Had the 600 MPa value applied here, the 8.8 dry torque would be 167 ft-lb instead of 161. The break is why class 10.9 sits about 43% above 8.8 at M16 but only about 38% above it at M20, where 8.8 dry is 325 ft-lb, about twice the M16 figure.
Class 9.8 is defined only up to M16 1 and is not in these tables.
M16 next to 5/8 inch
M16 (16 mm) is slightly larger than 5/8 in (15.9 mm). On the same basis an M16 class 8.8 takes about 7% more torque than a 5/8-11 Grade 5 and clamps about 7% more.
Wrench size
An M16 hex head is 24 mm across the flats in both ISO 4014/4017 and DIN 931/933 2; the ISO/DIN split that affects M10 to M14 does not apply.
Which class you have
The class symbol and the maker’s mark are on the head 1; see the bolt grades page. Class 12.9 dry is 270 ft-lb (365 N·m).
When the chart does not apply
ISO 898-1 states that the up-to-16 mm class 8.8 values do not apply to structural bolting, where the over-16 mm column is used from M12 1; see structural bolts. Lubrication also matters at this torque: class 8.8 with moly paste (K 0.11) 5 is 89 ft-lb, little more than half the dry 161 ft-lb. See dry vs lubricated torque.
Sources
- 1
- 2
- 3
- 4
- 5Henkel Corporation (LOCTITE), LOCTITE LB 8012 Moly Paste TDS, April 2015Checked 21 Oct 2026
Spotted a value that doesn’t match its source? Report an error
Related
- 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.
- M20M20 x 2.5 bolt torque: 325 ft-lb (441 N·m) for class 8.8 and 450 ft-lb (610 N·m) for 10.9 dry, plus 12.9, M20 x 1.5 fine, zinc and oiled values.
- 5/8 in5/8-11 Grade 5 bolt torque is 150 ft-lb dry and Grade 8 is 212 ft-lb. Charts for 5/8-11 and 5/8-18 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.
- 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.