Torque Converter
Torque is a measure of rotational force — the tendency of a force to rotate an object around an axis. It is calculated as the product of force and the perpendicular distance from the axis of rotation (lever arm). The SI unit is the Newton-meter (N·m), but engineers and mechanics frequently work with kilogram-force meters (kgf·m), pound-force feet (lbf·ft), and pound-force inches (lbf·in) depending on their region and industry.
This converter lets you instantly translate a torque value between all four common units using precise conversion factors. Enter a value in any unit — Newton-meters, kgf·m, lbf·ft, or lbf·in — and see the equivalent in every other unit at once. All calculations are performed client-side with no rounding ambiguity.
How it works
All units are converted through the Newton-meter base. Factors: 1 kgf·m = 9.80665 N·m; 1 lbf·ft = 1.35582 N·m; 1 lbf·in = 0.11298 N·m. To convert from unit A to unit B: value_B = value_A × factor_A / factor_B.
Use cases
- Converting engine torque specs between metric (N·m) and imperial (lbf·ft) for automotive work
- Verifying bolt tightening torques when using a wrench calibrated in different units
- Translating torque ratings for electric motors between SI and legacy engineering units
- Comparing torque specifications in international product manuals and data sheets
- Educational exercises in physics and mechanical engineering involving rotational dynamics
Frequently asked questions
How do I convert Newton-meters to pound-force feet?
Divide the value in Newton-meters by 1.35582, since 1 lbf·ft = 1.35582 N·m. For example, 100 N·m ÷ 1.35582 ≈ 73.76 lbf·ft. To go the other way, multiply the lbf·ft value by 1.35582.
What is the difference between N·m, kgf·m, and lbf·ft?
They all measure the same physical quantity — torque, or rotational force — but in different unit systems. The Newton-meter is the SI unit, kgf·m is a metric gravitational unit common in older manuals and some regions, and lbf·ft is the imperial unit used mainly in the United States. The fixed relationships are 1 kgf·m = 9.80665 N·m and 1 lbf·ft = 1.35582 N·m.
Why does 1 kgf·m equal 9.80665 N·m?
A kilogram-force (kgf) is defined as the force that standard gravity exerts on a mass of one kilogram, and standard gravity is 9.80665 m/s². So one kilogram-force equals 9.80665 Newtons, and applying that force on a one-meter lever arm gives 9.80665 N·m of torque.
How do I use a torque wrench when the spec is in a different unit?
Convert the specified torque into the unit your wrench is calibrated in before tightening. For example, a bolt spec of 40 N·m corresponds to about 29.5 lbf·ft (40 ÷ 1.35582). Converting first matters because over- or under-tightening fasteners can damage threads or let parts loosen.
How is torque calculated in physics?
Torque is the product of a force and the perpendicular distance from the axis of rotation to the line of action of that force, often called the lever arm. Applying 10 N of force at the end of a 0.5 m wrench perpendicular to the handle produces 5 N·m of torque. A longer lever arm produces more torque for the same force.