ENGINEERING TOOL
M30 Bolt Torque Chart: Specs, Values & Settings
Class 8.8 · Target preload (kN) 251.3
| Dry / Black | 1508 N·m 1357–1659 |
| Electro Zinc | 1282 N·m 1131–1508 |
| Hot-Dip Galv. | 1659 N·m 1357–1885 |
| Oiled | 980 N·m 905–1131 |
M30 bolt torque spec: class 8.8 dry is 1508 N·m (1112 ft·lb). Values cover six property classes across five friction states — dry, zinc, HDG, oiled and anti-seize. K-factor method, basis fully disclosed.
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Torque by Property Class and Friction State
Quick answer: class 8.8 · dry / black ≈ 1508 N·m (1357–1659); other classes and friction states below.
| Class | Rp0.2 (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 |
|---|---|---|---|---|---|---|---|
| 4.8 | 340 | 133.5 | 801 721–881 | 681 601–801 | 881 721–1001 | 521 481–601 | 401 320–481 |
| 8.8 | 640 | 251.3 | 1508 1357–1659 | 1282 1131–1508 | 1659 1357–1885 | 980 905–1131 | 754 603–905 |
| 10.9 | 940 | 369.1 | 2215 1993–2436 | 1883 1661–2215 | 2436 1993–2769 | 1440 1329–1661 | 1107 886–1329 |
| 12.9 | 1100 | 432 | 2592 2333–2851 | 2203 1944–2592 | 2851 2333–3240 | 1685 1555–1944 | 1296 1037–1555 |
| A2-70 | 450 | 176.7 | 1060 954–1166 | 901 795–1060 | 1166 954–1325 | 689 636–795 | 530 424–636 |
| A4-80 | 600 | 235.6 | 1414 1272–1555 | 1202 1060–1414 | 1555 1272–1767 | 919 848–1060 | 707 565–848 |
Cell shows the typical value; the small line below is the range (min–max).
References
- ISO 898-1:2013 — Mechanical properties of fasteners made of carbon and alloy steel
- ISO 3506-1:2020 — Mechanical properties of corrosion-resistant stainless steel fasteners (A2/A4)
- GB/T 3098.1-2010 — Mechanical properties of bolts, screws and studs (CN national standard, official full text)
- GB/T 3098.6-2014 — Mechanical properties of stainless steel bolts, screws and studs (CN, official full text)
- ISO 16047:2005 — Fasteners: torque/clamp force testing (K-factor measurement method)
- Machinery's Handbook (30th ed.) — empirical K-factor ranges
- Machine Design — anti-seize compound friction test (K≈0.10)
Fine-Thread Torque Matrix
Fine-thread series (M30 × 2 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 M30 As = 621 mm²).
| Class | Rp0.2 (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 |
|---|---|---|---|---|---|---|---|
| 4.8 | 340 | 147.8 | 887 798–975 | 754 665–887 | 975 798–1108 | 576 532–665 | 443 355–532 |
| 8.8 | 640 | 278.2 | 1669 1502–1836 | 1419 1252–1669 | 1836 1502–2087 | 1085 1002–1252 | 835 668–1002 |
| 10.9 | 940 | 408.6 | 2452 2207–2697 | 2084 1839–2452 | 2697 2207–3065 | 1594 1471–1839 | 1226 981–1471 |
| 12.9 | 1100 | 478.2 | 2869 2582–3156 | 2439 2152–2869 | 3156 2582–3586 | 1865 1721–2152 | 1435 1148–1721 |
| A2-70 | 450 | 195.6 | 1174 1056–1291 | 998 880–1174 | 1291 1056–1467 | 763 704–880 | 587 469–704 |
| A4-80 | 600 | 260.8 | 1565 1408–1721 | 1330 1174–1565 | 1721 1408–1956 | 1017 939–1174 | 782 626–939 |
Cell shows the typical value; the small line below is the range (min–max).
Basis of Calculation & Sources
Calculation basis
- 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 (M30 As = 561 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).
Scope & limits
- 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.
Cite this chart
YAXIIO. M30 Bolt Torque Chart: Specs, Values & Settings. https://www.yaxiio.com/en/tools/bolt-torque-chart/m30 (accessed 2026-10-29).
Free to cite and embed — attribution required: “YAXIIO” + a link to this page.
FAQ
What is the target preload for an M30 bolt?
At 70% of Rp0.2: class 4.8 ≈ 133.5 kN, 8.8 ≈ 251.3 kN, 10.9 ≈ 369.1 kN; stainless A2-70 ≈ 176.7 kN and A4-80 ≈ 235.6 kN.
Can I use carbon-steel torque values for stainless M30 (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).
Next: work out your order, or pick the size by standard
Related References
Bolt Torque Calculator
Interactive version: fine threads, imperial, stud bolts, custom K and torque check — this size is pre-filled.
M30 Hex Bolt Weight Chart
Per-piece and per-1,000-pcs weights across the full length series of the same size.
Tap Drill for the Thread Being Tightened
The hole under the bolt: rule tap drill value plus the nearest drill bit in the set, stated ahead of the torque tables.
Disclaimer: This chart is an engineering estimation for selection and budgeting only. It does not constitute assembly instructions or acceptance criteria.