ENGINEERING TOOL
M16 Bolt Torque Chart: Specs, Values & Settings
Class 8.8 · Target preload (kN) 70.3
| Dry / Black | 225 N·m 203–248 |
| Electro Zinc | 191 N·m 169–225 |
| Hot-Dip Galv. | 248 N·m 203–281 |
| Oiled | 146 N·m 135–169 |
M16 bolt torque spec: class 8.8 dry is 225 N·m (166 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 ≈ 225 N·m (203–248); 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 | 37.4 | 120 108–132 | 102 90–120 | 132 108–149 | 78 72–90 | 60 48–72 |
| 8.8 | 640 | 70.3 | 225 203–248 | 191 169–225 | 248 203–281 | 146 135–169 | 113 90–135 |
| 10.9 | 940 | 103.3 | 331 298–364 | 281 248–331 | 364 298–413 | 215 198–248 | 165 132–198 |
| 12.9 | 1100 | 120.9 | 387 348–426 | 329 290–387 | 426 348–484 | 251 232–290 | 193 155–232 |
| A2-70 | 450 | 49.5 | 158 142–174 | 135 119–158 | 174 142–198 | 103 95–119 | 79 63–95 |
| A4-80 | 600 | 65.9 | 211 190–232 | 179 158–211 | 232 190–264 | 137 127–158 | 106 84–127 |
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 (M16 × 1.5 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 M16 As = 167 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 | 39.7 | 127 114–140 | 108 95–127 | 140 114–159 | 83 76–95 | 64 51–76 |
| 8.8 | 640 | 74.8 | 239 215–263 | 203 180–239 | 263 215–299 | 156 144–180 | 120 96–144 |
| 10.9 | 940 | 109.9 | 352 316–387 | 299 264–352 | 387 316–440 | 229 211–264 | 176 141–211 |
| 12.9 | 1100 | 128.6 | 411 370–453 | 350 309–411 | 453 370–514 | 267 247–309 | 206 165–247 |
| A2-70 | 450 | 52.6 | 168 152–185 | 143 126–168 | 185 152–210 | 109 101–126 | 84 67–101 |
| A4-80 | 600 | 70.1 | 224 202–247 | 191 168–224 | 247 202–281 | 146 135–168 | 112 90–135 |
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 (M16 As = 157 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. M16 Bolt Torque Chart: Specs, Values & Settings. https://www.yaxiio.com/en/tools/bolt-torque-chart/m16 (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 M16 bolt?
At 70% of Rp0.2: class 4.8 ≈ 37.4 kN, 8.8 ≈ 70.3 kN, 10.9 ≈ 103.3 kN; stainless A2-70 ≈ 49.5 kN and A4-80 ≈ 65.9 kN.
Can I use carbon-steel torque values for stainless M16 (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.
M16 Hex Bolt Weight Chart
Per-piece and per-1,000-pcs weights across the full length series of the same size.
M16 Hex Key Size Chart
Which hex key (Allen wrench) fits a socket head cap screw of the same size: socket width across flats, key long and short arm lengths, and unit weight on the GB/T 70.1 + GB/T 5356 basis.
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.