An M10 Class 8.8 bolt takes 50.5 N·m (37.2 ft·lbs) dry, or 37.8 N·m oiled. Every size from M3 to M64 is listed below — click a value for the full spec including all six surface conditions and fine-thread figures.
| Size | Pitch | N·m (dry) | ft·lbs (dry) | N·m (oiled) |
|---|---|---|---|---|
| M3 | 0.5 mm | 1.3 | 1.0 | 1.0 |
| M4 | 0.7 mm | 3.1 | 2.3 | 2.3 |
| M5 | 0.8 mm | 6.2 | 4.6 | 4.6 |
| M6 | 1.0 mm | 10.5 | 7.7 | 7.9 |
| M7 | 1.0 mm | 17.6 | 13.0 | 13.2 |
| M8 | 1.25 mm | 25.5 | 18.8 | 19.1 |
| M10 | 1.5 mm | 50.5 | 37.2 | 37.8 |
| M12 | 1.75 mm | 88.0 | 64.9 | 66.0 |
| M14 | 2.0 mm | 140.6 | 103.7 | 105.5 |
| M16 | 2.0 mm | 218.1 | 160.9 | 163.6 |
| M18 | 2.5 mm | 311.8 | 230.0 | 233.9 |
| M20 | 2.5 mm | 440.6 | 325.0 | 330.5 |
| M22 | 2.5 mm | 600.7 | 443.1 | 450.5 |
| M24 | 3.0 mm | 761.4 | 561.6 | 571.1 |
| M27 | 3.0 mm | 1116.4 | 823.4 | 837.3 |
| M30 | 3.5 mm | 1513.6 | 1116.4 | 1135.2 |
| M33 | 3.5 mm | 2059.8 | 1519.2 | 1544.9 |
| M36 | 4.0 mm | 2646.2 | 1951.7 | 1984.6 |
| M39 | 4.0 mm | 3425.8 | 2526.7 | 2569.3 |
| M42 | 4.5 mm | 4237.0 | 3125.1 | 3177.8 |
| M45 | 4.5 mm | 5289.7 | 3901.5 | 3967.3 |
| M48 | 5.0 mm | 6364.2 | 4694.0 | 4773.1 |
| M52 | 5.0 mm | 8226.2 | 6067.3 | 6169.6 |
| M56 | 5.5 mm | 10231.2 | 7546.1 | 7673.4 |
| M64 | 6.0 mm | 15413.8 | 11368.6 | 11560.3 |
Dry/plain steel, K = 0.20 · Coarse thread · Clamp load 75% of proof load · Click any N·m value for full details
Identification: Head stamped 8.8. The two-part number is the strength code: 800 MPa tensile, 640 MPa yield.
Material: Medium carbon steel, quenched and tempered, proof stress 580 MPa per ISO 898-1.
Where it is used: The workhorse high-strength metric grade — automotive engines, structural connections, flanged joints and general machinery.
Worth knowing: ISO 898-1 specifies two strength tiers for class 8.8: bolts up to M16 and bolts above M16 have slightly different minimum values, which is reflected in the figures below.
Every figure comes from T = K × D × F, where K is the nut factor (0.20 dry, 0.15 oiled), D is nominal diameter in metres, and F is clamp load set at 75% of proof load. Proof stress and tensile stress area come from ISO 898-1.
These are engineering reference values for a standard hex bolt in a steel joint. Where a manufacturer publishes a specific figure, use theirs. Full methodology →
It depends on diameter. An M8 Class 8.8 takes 25.5 N·m (18.8 ft·lbs), an M10 takes 50.5 N·m (37.2 ft·lbs), and an M12 takes 88.0 N·m (64.9 ft·lbs) — all dry, plain steel, coarse thread. The full table covers M3 to M64.
The first number is one hundredth of the minimum tensile strength in MPa, and the second is ten times the ratio of yield to tensile strength. So 8.8 means 800 MPa tensile and a yield point at 80% of that — 640 MPa.
Medium carbon steel, quenched and tempered, with a minimum tensile strength of 800 MPa, yield strength of 640 MPa and proof stress of 580 MPa per ISO 898-1.
Yes. Oil lowers the nut factor from about 0.20 to 0.15, so the same clamp load needs roughly 25% less torque. An M10 Class 8.8 goes from 50.5 N·m dry to 37.8 N·m oiled — using the dry figure on an oiled bolt risks exceeding yield.