Torque Converter

How to use the torque converter

1. Type a torque in Value. A decimal point or a decimal comma both work.
2. Choose the starting unit in From and the target unit in To, for example newton metre and pound-force foot (lb-ft).
3. The result appears as you type, with the full line below it (“1 N·m ≈ 0.73756215 lbf·ft”). Copy copies that line, ready to paste into a workshop note.
4. Swap units (⇄) reverses the conversion, for example to turn a US service manual’s lb-ft into N·m for your torque wrench.
5. Significant figures sets the rounding; “≈” marks a rounded value. Three or four figures are plenty for a torque wrench.

The page also shows the torque in every unit, a quick table for the selected pair, typical tightening values (bicycle stem, spark plug, wheel nuts), the peak torque of a car engine, and each unit expressed in newton metres.

The units

Torque is a force multiplied by the length of the lever arm, so every torque unit is a force unit times a length unit:

• Newton metre (N·m): the SI unit. 1 N·cm = 0.01 N·m, the unit of electric screwdrivers.
• Pound-force foot (lbf·ft, often written lb-ft or ft-lb): 4.4482216152605 N × 0.3048 m = 1.3558179483 N·m exactly.
• Pound-force inch (lbf·in, lb-in or in-lb): 1/12 of a lb-ft, 0.1129848290 N·m, used for small fasteners.
• Ounce-force inch (ozf·in): 1/16 of a lb-in, about 0.00706 N·m, common for small motors.
• Kilogram-force metre (kgf·m, “mkg”): 9.80665 N·m exactly, found in older European and Japanese manuals.
• Kilogram-force centimetre (kgf·cm): 0.0980665 N·m, the usual rating of hobby servos.

The pound-force and kilogram-force both use standard gravity (9.80665 m/s²), so all of these factors are exact.

Torque and energy: same dimension, different meaning

A newton metre and a joule have the same SI dimension (kg·m²/s²), yet they measure different things. Energy (work) is a force times a distance along the direction of the force. Torque is a force times a lever arm perpendicular to it: a turning effect, which can exist without anything moving. A wrench held still on a stuck bolt applies torque but does no work.

The link between the two is the angle: work = torque × angle in radians. One full turn at 10 N·m does 10 × 2π ≈ 62.8 J of work. That is why the SI recommends writing torque in N·m, never in joules, and why the order “lb-ft” (torque) versus “ft-lb” (energy) is sometimes used to tell them apart. This tool only converts torque; for joules and foot-pounds of energy, use an energy converter.

Torque also links to engine power: power (W) = torque (N·m) × angular speed (rad/s). In workshop units, kW = N·m × rpm ÷ 9,549 and hp = lb-ft × rpm ÷ 5,252.