ENGINEERING TOOL

M10 Bolt Torque Chart

Target preload and tightening torque ranges (min–typ–max) for M10 bolts across six property classes and five friction states. K-factor method, basis fully disclosed.

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Torque by Property Class and Friction State

Quick answer: class 8.8 · electro zinc ≈ 44 N·m (39–52); other classes and friction states below.

ClassRp0.2 (MPa)Target preload (kN)Dry / Black
K 0.18–0.22 · N·m
Electro Zinc
K 0.15–0.2 · N·m
Hot-Dip Galv.
K 0.18–0.25 · N·m
Oiled
K 0.12–0.15 · N·m
Wax / PTFE / Anti-seize
K 0.08–0.12 · N·m
4.834013.828
25–30
23
21–28
30
25–35
18
17–21
14
11–17
8.86402652
47–57
44
39–52
57
47–65
34
31–39
26
21–31
10.994038.276
69–84
65
57–76
84
69–95
50
46–57
38
31–46
12.9110044.789
80–98
76
67–89
98
80–112
58
54–67
45
36–54
A2-7045018.337
33–40
31
27–37
40
33–46
24
22–27
18
15–22
A4-8060024.449
44–54
41
37–49
54
44–61
32
29–37
24
19–29

Cell shows the typical value; the small line below is the range (min–max).

Fine-Thread Torque Matrix

Fine-thread series (M10 × 1 mm) target preload and tightening torque ranges, same basis as the coarse chart; the fine-thread stress area As follows ISO 898-1:2013 Table 6 (this page takes M10 As = 64.5 mm²).

ClassRp0.2 (MPa)Target preload (kN)Dry / Black
K 0.18–0.22 · N·m
Electro Zinc
K 0.15–0.2 · N·m
Hot-Dip Galv.
K 0.18–0.25 · N·m
Oiled
K 0.12–0.15 · N·m
Wax / PTFE / Anti-seize
K 0.08–0.12 · N·m
4.834015.431
28–34
26
23–31
34
28–38
20
18–23
15
12–18
8.864028.958
52–64
49
43–58
64
52–72
38
35–43
29
23–35
10.994042.485
76–93
72
64–85
93
76–106
55
51–64
42
34–51
12.9110049.799
89–109
84
74–99
109
89–124
65
60–74
50
40–60
A2-7045020.341
37–45
35
30–41
45
37–51
26
24–30
20
16–24
A4-8060027.154
49–60
46
41–54
60
49–68
35
33–41
27
22–33

Cell shows the typical value; the small line below is the range (min–max).

Basis of Calculation & Sources

Torque follows the K-factor (nut factor) method T = K·D·F: D is the nominal diameter and F the target preload = 70% of Rp0.2 × thread stress area (M10 As = 58 mm²). Yield strengths are published values from ISO 898-1 (carbon/alloy steel) and ISO 3506-1 (stainless A2/A4). K follows published empirical ranges per friction condition (Machinery's Handbook; the wax/PTFE/anti-seize band K≈0.10 follows Machine Design test data). The grease/MoS₂ band (K≈0.11) nearly overlaps anti-seize and is available in the calculator instead of a separate column.

Stainless note: A2/A4 austenitic thread pairs gall easily under frictional heating. Always apply anti-seize and follow the Wax/PTFE/Anti-seize column (K≈0.10).

Boundary: this chart is a simplified K-factor estimate, not a full VDI 2230 analysis (which accounts for joint resilience, embedment and assembly method). Friction is the dominant variable — no single torque value exists without its friction state. Always follow the design specification or manufacturer torque table.

FAQ

What is the tightening torque for an M10 class 8.8 bolt?

It depends on the friction state (typical values at 70% of Rp0.2 target preload): oiled ≈ 34 N·m, electro zinc ≈ 44 N·m, hot-dip galvanized ≈ 57 N·m, dry/black ≈ 52 N·m, anti-seize ≈ 26 N·m. See the matrix above for ranges — no single torque value exists without its friction state.

What is the target preload for an M10 bolt?

At 70% of Rp0.2: class 4.8 ≈ 13.8 kN, 8.8 ≈ 26 kN, 10.9 ≈ 38.2 kN; stainless A2-70 ≈ 18.3 kN and A4-80 ≈ 24.4 kN.

Can I use carbon-steel torque values for stainless M10 (A2-70/A4-80)?

No. The classes have different yield strengths (A2-70 = 450 MPa, A4-80 = 600 MPa), so target preloads differ; and stainless thread pairs gall easily — always apply anti-seize and follow the Wax/PTFE/Anti-seize column (K≈0.10).

What basis are these torque values calculated on?

The K-factor method T = K·D·F with target preload = 70% of Rp0.2 × stress area (yield strengths per ISO 898-1 / ISO 3506-1 published values) and K per published empirical friction ranges. Estimated values, not assembly instructions; run a full VDI 2230 analysis for critical joints.

Related References

Disclaimer: This chart is an engineering estimation for selection and budgeting only. It does not constitute assembly instructions or acceptance criteria.

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