ENGINEERING TOOL
M27 Bolt Torque Chart: Specs, Values & Settings
Class 8.8 · Target preload (kN) 205.6
| Dry / Black | 1110 N·m 999–1221 |
| Electro Zinc | 944 N·m 833–1110 |
| Hot-Dip Galv. | 1221 N·m 999–1388 |
| Oiled | 722 N·m 666–833 |
M27 bolt torque spec: class 8.8 dry is 1110 N·m (819 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 ≈ 1110 N·m (999–1221); 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 | 109.2 | 590 531–649 | 501 442–590 | 649 531–737 | 383 354–442 | 295 236–354 |
| 8.8 | 640 | 205.6 | 1110 999–1221 | 944 833–1110 | 1221 999–1388 | 722 666–833 | 555 444–666 |
| 10.9 | 940 | 302 | 1631 1468–1794 | 1386 1223–1631 | 1794 1468–2039 | 1060 979–1223 | 815 652–979 |
| 12.9 | 1100 | 353.4 | 1909 1718–2099 | 1622 1431–1909 | 2099 1718–2386 | 1241 1145–1431 | 954 763–1145 |
| A2-70 | 450 | 144.6 | 781 703–859 | 664 586–781 | 859 703–976 | 507 468–586 | 390 312–468 |
| A4-80 | 600 | 192.8 | 1041 937–1145 | 885 781–1041 | 1145 937–1301 | 677 625–781 | 521 416–625 |
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 (M27 × 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 M27 As = 496 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 | 118 | 637 574–701 | 542 478–637 | 701 574–797 | 414 382–478 | 319 255–382 |
| 8.8 | 640 | 222.2 | 1200 1080–1320 | 1020 900–1200 | 1320 1080–1500 | 780 720–900 | 600 480–720 |
| 10.9 | 940 | 326.4 | 1762 1586–1939 | 1498 1322–1762 | 1939 1586–2203 | 1146 1057–1322 | 881 705–1057 |
| 12.9 | 1100 | 381.9 | 2062 1856–2269 | 1753 1547–2062 | 2269 1856–2578 | 1341 1237–1547 | 1031 825–1237 |
| A2-70 | 450 | 156.2 | 844 759–928 | 717 633–844 | 928 759–1055 | 548 506–633 | 422 337–506 |
| A4-80 | 600 | 208.3 | 1125 1012–1237 | 956 844–1125 | 1237 1012–1406 | 731 675–844 | 562 450–675 |
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 (M27 As = 459 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. M27 Bolt Torque Chart: Specs, Values & Settings. https://www.yaxiio.com/en/tools/bolt-torque-chart/m27 (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 M27 bolt?
At 70% of Rp0.2: class 4.8 ≈ 109.2 kN, 8.8 ≈ 205.6 kN, 10.9 ≈ 302 kN; stainless A2-70 ≈ 144.6 kN and A4-80 ≈ 192.8 kN.
Can I use carbon-steel torque values for stainless M27 (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.
M27 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.