🔧 FUTEK Bolt Torque Calculator
Calculate precise clamping torque for any bolt size, grade, and material — imperial & metric
| Bolt Size | TPI | Grade 2 (ft-lb) | Grade 5 (ft-lb) | Grade 8 (ft-lb) | Stainless A2 (ft-lb) | Stress Area (in²) |
|---|---|---|---|---|---|---|
| 1/4‑20 | 20 | 4 | 6 | 9 | 5 | 0.0318 |
| 5/16‑18 | 18 | 8 | 12 | 18 | 10 | 0.0524 |
| 3/8‑16 | 16 | 15 | 24 | 35 | 20 | 0.0775 |
| 7/16‑14 | 14 | 24 | 38 | 56 | 32 | 0.1063 |
| 1/2‑13 | 13 | 37 | 59 | 88 | 50 | 0.1419 |
| 9/16‑12 | 12 | 52 | 84 | 125 | 71 | 0.1820 |
| 5/8‑11 | 11 | 73 | 117 | 174 | 99 | 0.2260 |
| 3/4‑10 | 10 | 128 | 206 | 308 | 175 | 0.3340 |
| 7/8‑9 | 9 | 206 | 330 | 492 | 280 | 0.4620 |
| 1‑8 | 8 | 308 | 494 | 737 | 420 | 0.6060 |
| Bolt Size | Pitch (mm) | Class 8.8 (N·m) | Class 10.9 (N·m) | Class 12.9 (N·m) | A2-70 SS (N·m) | Stress Area (mm²) |
|---|---|---|---|---|---|---|
| M4 | 0.70 | 2.9 | 4.1 | 4.8 | 2.5 | 8.78 |
| M5 | 0.80 | 5.8 | 8.1 | 9.5 | 5.0 | 14.18 |
| M6 | 1.00 | 9.9 | 14 | 16 | 8.5 | 20.12 |
| M8 | 1.25 | 24 | 34 | 40 | 20 | 36.61 |
| M10 | 1.50 | 47 | 67 | 78 | 40 | 58.00 |
| M12 | 1.75 | 82 | 115 | 135 | 70 | 84.27 |
| M14 | 2.00 | 130 | 182 | 213 | 111 | 115.44 |
| M16 | 2.00 | 200 | 281 | 328 | 171 | 156.67 |
| M20 | 2.50 | 390 | 550 | 642 | 334 | 244.79 |
| M24 | 3.00 | 676 | 952 | 1112 | 579 | 352.50 |
| Condition | K Factor | Effect on Torque | Notes |
|---|---|---|---|
| As-received, dry | 0.20 | Baseline | Standard uncoated steel |
| Slightly oily | 0.17 | –15% | Light machine oil residue |
| Oil / grease | 0.15 | –25% | Grease or engine oil applied |
| Zinc-plated | 0.17 | –15% | Electroplated zinc |
| Hot-dip galvanized | 0.25 | +25% | Requires more torque |
| Anti-seize compound | 0.13 | –35% | Copper or nickel anti-seize |
| PTFE / Loctite | 0.12 | –40% | Thread-locking compound |
| Cadmium-plated | 0.13 | –35% | Aerospace fasteners |
| Application | Typical Bolt | Torque (ft-lb) | Torque (N·m) | Grade / Class |
|---|---|---|---|---|
| Engine cylinder head | M10 / 3/8 | 25–35 | 34–47 | Grade 8 / 10.9 |
| Automotive wheel lug | M12 / 1/2 | 80–100 | 108–135 | Grade 8 / 10.9 |
| Structural steel joint | 3/4‑10 | 200–310 | 271–420 | A325 / Grade 8 |
| Machinery base plate | M16 | 145–200 | 197–271 | Class 10.9 |
| Pipe flange (Class 150) | 5/8‑11 | 100–130 | 136–176 | Grade 5 / 8.8 |
| Pressure vessel cover | M20 | 280–400 | 380–542 | Class 10.9 / 12.9 |
| Load cell mounting (FUTEK) | 1/4‑28 | 5–8 | 7–11 | Grade 8 / Class 12.9 |
| Aluminum bracket | M8 / 5/16 | 10–16 | 14–22 | Grade 5 / Class 8.8 |
FUTEK makes sensors in United States for control load, Torque, force, multi-axis loads and pressure. Besides simply making, the company offers fitting devices, services for calibration and software for measurement under his mark. Among the useful resources on their website stands calculator for Torque of bolts, practical aid that removes the need guess, what exact value truly use for bolts and screws.
Such calculator helps you stay true to limits of safety. It reduces the dangers of too much tightening (or too little tightening) on bolt. That truly matters, when one cares about important parts or assemblies, where failure can not happen.
FUTEK Tools for Measuring Bolt Torque and Clamp Force
The donut load cells of FUTEK are truly cleverly designed. They detect axial force directly, what avoids the annoying problems with accuracy, that otherwise appear. What comes out?
Reliable and repeatable measures, that you truly can believe. Here why they fit this well as answer for calibration of Torque wrenches, checking of preload and testing of futek bolt qualities. Engineers rely on them, to ensure, that parts stay set with real accuracy and assurance.
Measuring clamp force matters for all kinds of bolted assemblies. It is key also in metal die-casting, where steady clamp of template directly affects, whether safe the process and how looks the final product.
The LTH Donut Load Cell… Sometimes called through-hole load cell, sits clamped between the head of bolt and the washer. From that place it catches the real binding forse of the bolt and the test load, while you add Torque.
In typical assembly of bolt and washer, average donut or through-hole load cells rest on the bolt self. Then rotary Torque sensor seizes the Torque, that electric drivers apply in the same assembly. Users can connect both the donut load cell and the rotary Torque sensor too USB solutions of FUTEK, to follow, what each sensor truly shows.
Here the TRH Hex-Drive Rotary Torque Sensor. One sets it to strong tool, to control Torque and turn angle, while it tightens bolt against fixed plate. Those sensors allow efficient tightening by means of tools without need seize exact readings of Torque (something), what otherwise wood be truly hard.
The website of FUTEK goes beyond only the Torque calculator. It has online tools for units convert, calculations of resolution, data about calibration, factors of outside loads and many other quick helps. The whole range of products includes load cells, strong sensors, Torque sensors, close sensors, multi-axis sensors, together with special sensors and electronics for sorting.
Some test M5 bolt by means of the online calculator of FUTEK in metric system at 5 N-m and get almost 517 kilos of tension. Here exactly, what thetool intends to reach, fast results without trouble.
