Torque Converter

Torque is the rotational or twisting effect produced when a force acts at a distance from a pivot point or axis of rotation. It is defined as τ = F × r, where F is the applied force and r is the perpendicular distance from the axis to the line of action of the force. Torque is the rotational analogue of linear force and is one of the most important quantities in mechanical, automotive, aerospace, and structural engineering.

The SI unit of torque is the Newton-meter (N·m). One Newton-meter is the torque produced by a force of one Newton applied perpendicularly at a distance of one meter from the axis. The Newton-meter is the standard in scientific literature, European automotive specifications, and international engineering codes including ISO and IEC standards.

In North America, the most common torque unit is the pound-force foot (lbf·ft), often abbreviated as ft·lb in automotive contexts. Engine torque specifications, lug nut tightening values, and structural bolt torque specs in US engineering are typically given in lbf·ft. For smaller torques in electronic assemblies, precision instruments, and micro-mechanisms, the pound-force inch (lbf·in) and ounce-force inch (ozf·in) are standard. The relationship is: 1 lbf·ft = 12 lbf·in = 192 ozf·in.

In the metric-gravitational system, torque is expressed as kilogram-force meter (kgf·m), kilogram-force centimeter, or gram-force centimeter. These units relate force to the gravitational weight of a mass and are common in older machinery documentation, some Asian industrial standards, and agricultural equipment. 1 kgf·m = 9.80665 N·m. The gram-force centimeter (gf·cm) is used for very small torques in instruments and precision devices.

In the CGS (centimeter-gram-second) system used in physics, torque is expressed in dyne-centimeter (dyn·cm). 1 N·m = 10⁷ dyn·cm. This converter also includes dyne-meter and dyne-millimeter for complete CGS coverage, supporting older physics literature and laboratory instrument calibration.

Torque and power are directly related by the equation P = τ × ω (Power = Torque × Angular Velocity in rad/s). A car engine producing 300 N·m of torque at 3000 RPM (314.16 rad/s) generates 300 × 314.16 = 94,248 W ≈ 94.2 kW ≈ 126 hp. Understanding and converting between torque units is therefore also essential for power calculations.

Typical torque values across engineering practice: Bicycle pedal bolt: 35–40 N·m. Car lug nut: 100–140 N·m (75–103 lbf·ft). Car engine peak torque: 150–600 N·m. Large truck engine: up to 3000 N·m. Industrial wind turbine gearbox input: millions of N·m. Micro servo motor: 0.1–5 N·m (1–44 lbf·in). Electronics screws: 0.2–0.5 N·m (2–4 lbf·in).

Fastener torque specification is one of the most common engineering uses of torque conversion. Maintenance manuals from US manufacturers specify torques in lbf·ft, while ISO and metric standards use N·m. Mechanics and technicians working on imported or exported equipment need fast, accurate conversion to ensure proper clamping forces without stripped threads or structural failure. Under-torquing causes joint slippage; over-torquing causes bolt failure or thread stripping.

In robotics, servo motor torque ratings given by Japanese and Korean manufacturers are often in kgf·cm, while European and American control software requires N·m. In testing equipment, torque sensors and dynamometers may output in lbf·ft, dyn·cm, or N·m depending on the instrument's origin. This torque converter supports all 17 standard units: newton meter, newton centimeter, newton millimeter, kilonewton meter, dyne meter, dyne centimeter, dyne millimeter, kilogram-force meter, kilogram-force centimeter, kilogram-force millimeter, gram-force meter, gram-force centimeter, gram-force millimeter, ounce-force foot, ounce-force inch, pound-force foot, and pound-force inch. All conversions are instant, precise to 12 significant digits, and completely free.