Class 10.9 bolt torque chart and strength

An M12 x 1.75 class 10.9 bolt takes 93 ft-lb (126 N·m) plain and dry or 70 ft-lb (94 N·m) oiled, for 52.5 kN of clamp load. Its 830 MPa proof stress applies in every size.

By the Torque Reference editors 4 sources cited Last reviewed 21 Oct 2026 Method

Contents8 sections

Key takeaways

10.9 means 1,000 MPa nominal tensile strength with yield at 0.9 of that ⁠¹.
Proof 830 MPa, yield 940 MPa, tensile 1,040 MPa, with no size break ⁠¹.
It takes about 43% more torque than 8.8 up to M16, and 17% less than 12.9.
SAE Grade 8 is the inch near-equivalent.

Quick facts

Proof stress	830 MPa (120.4 ksi)
Tensile	1,040 MPa (150.8 ksi)
Head marking	10.9 plus maker's mark
Inch near-equivalent	Grade 8

Class 10.9 strength

Sizes	Proof stress	Yield	Tensile
All sizes	830 MPa	940 MPa	1040 MPa

Sizes

Proof stress

Yield

Tensile

All sizes

830 MPa

940 MPa

1040 MPa

ISO 898-1 Table 3⁠¹.

Class 10.9 torque chart

Size	Dry K 0.20⁠²	Zinc K 0.18⁠²	Oiled K 0.15⁠²
M3 x 0.5	17 in-lb1.9 N·m	15 in-lb1.7 N·m	12 in-lb1.4 N·m
M4 x 0.7	39 in-lb4.4 N·m	35 in-lb3.9 N·m	29 in-lb3.3 N·m
M5 x 0.8	78 in-lb8.8 N·m	70 in-lb8.0 N·m	59 in-lb6.6 N·m
M6 x 1	11 ft-lb15 N·m	120 in-lb14 N·m	100 in-lb11 N·m
M8 x 1.25	27 ft-lb36 N·m	24 ft-lb33 N·m	20 ft-lb27 N·m
M10 x 1.5	53 ft-lb72 N·m	48 ft-lb65 N·m	40 ft-lb54 N·m
M12 x 1.75	93 ft-lb126 N·m	84 ft-lb113 N·m	70 ft-lb94 N·m
M14 x 2	148 ft-lb200 N·m	133 ft-lb180 N·m	111 ft-lb150 N·m
M16 x 2	231 ft-lb313 N·m	208 ft-lb281 N·m	173 ft-lb235 N·m
M20 x 2.5	450 ft-lb610 N·m	405 ft-lb549 N·m	337 ft-lb458 N·m
M24 x 3	778 ft-lb1,055 N·m	700 ft-lb949 N·m	583 ft-lb791 N·m
M30 x 3.5	1,545 ft-lb2,095 N·m	1,391 ft-lb1,886 N·m	1,159 ft-lb1,572 N·m

Size

Dry K 0.20⁠²

Zinc K 0.18⁠²

Oiled K 0.15⁠²

M3 x 0.5

17 in-lb1.9 N·m

15 in-lb1.7 N·m

12 in-lb1.4 N·m

M4 x 0.7

39 in-lb4.4 N·m

35 in-lb3.9 N·m

29 in-lb3.3 N·m

M5 x 0.8

78 in-lb8.8 N·m

70 in-lb8.0 N·m

59 in-lb6.6 N·m

M6 x 1

11 ft-lb15 N·m

120 in-lb14 N·m

100 in-lb11 N·m

M8 x 1.25

27 ft-lb36 N·m

24 ft-lb33 N·m

20 ft-lb27 N·m

M10 x 1.5

53 ft-lb72 N·m

48 ft-lb65 N·m

40 ft-lb54 N·m

M12 x 1.75

93 ft-lb126 N·m

84 ft-lb113 N·m

70 ft-lb94 N·m

M14 x 2

148 ft-lb200 N·m

133 ft-lb180 N·m

111 ft-lb150 N·m

M16 x 2

231 ft-lb313 N·m

208 ft-lb281 N·m

173 ft-lb235 N·m

M20 x 2.5

450 ft-lb610 N·m

405 ft-lb549 N·m

337 ft-lb458 N·m

M24 x 3

778 ft-lb1,055 N·m

700 ft-lb949 N·m

583 ft-lb791 N·m

M30 x 3.5

1,545 ft-lb2,095 N·m

1,391 ft-lb1,886 N·m

1,159 ft-lb1,572 N·m

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.

What 10.9 means

In ISO 898-1 designations, “10” is the nominal tensile strength in hundreds of MPa. “.9” means yield is 90% of the tensile strength ⁠¹. The minimum values are 830 MPa proof stress, 940 MPa 0.2% proof strength (yield) and 1,040 MPa tensile, the same for every size ⁠¹. ISO 898-1 covers carbon and alloy steel bolts ⁠¹. Its material and heat-treatment requirements are not in the free preview this site used, so they are not stated here.

The head carries “10.9” and the maker’s mark. “010.9” marks reduced loadability ⁠¹.

Strength and clamp load

Class 10.9 has no step at M16, unlike 8.8. Its advantage over 8.8 is therefore larger in small sizes:

M16 and smaller: 830 against 580 MPa proof, so 43% more clamp and torque.
M20 and up: 830 against 600 MPa, so 38% more.

ISO lists the M12 10.9 proof load as 70,000 N ⁠¹. 75% of that is the 52.5 kN clamp load behind the chart values ⁠². At M12, that is 93 ft-lb dry, 84 ft-lb zinc-plated and 70 ft-lb oiled. At M10 the values are 53, 48 and 40 ft-lb.

Compared with other classes

At the same size and condition:

12.9: 970 ÷ 830, about 17% more in every size.
8.8: about 30% less up to M16, and 28% less above M16.
SAE Grade 8: 120 ksi proof is 827 MPa and 150 ksi tensile is 1,034 MPa ⁠⁴. That is within 1% of 10.9 ⁠². The torque is not interchangeable, because the diameters and threads differ. A 1/2-13 Grade 8 bolt (12.7 mm) takes 107 ft-lb dry, against 93 for an M12 10.9.

Mixing up the class columns has a cost either way. An 8.8 value on a 10.9 bolt gives only about 70% of the 10.9 clamp load. The opposite mistake is worse: a 10.9 value on an 8.8 bolt asks for 43% more tension than the 8.8 basis.

Matching nut

The nut’s proof strength should be at least the bolt’s 1,040 MPa tensile strength ⁠². In the older ISO 898-2 table, class 10 nuts are rated at 1,040 MPa up to M10, 1,050 MPa from M10 to M16, and 1,060 MPa from M16 to M39 ⁠². That meets the rule. A class 8 nut, at 880–920 MPa, does not. Current ISO 898-2 values were not verified for this page.

For dry versus oiled threads and coatings, see the lubricated torque calculator.

Sources

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