Torque is a turning force: a force applied at a distance from a pivot. Repair manuals, wrench scales and engine specs express it in at least half a dozen units depending on the country and the size of the job — newton meters in metric manuals, pound-feet on US torque wrenches, inch-pounds for small fasteners and kilogram-force meters in older Japanese and European specs. This converter switches between them using exact definitions and, if you give it a speed, tells you how much power that torque delivers.
How to use the torque converter
- Enter the torque value and choose its unit in From.
- Choose the unit you need in To. Every other unit appears in the table below the result.
- Optionally enter a speed in rpm. The calculator adds the power produced at that speed in kilowatts and horsepower.
Torque formula and factors
Torque is force times the perpendicular lever arm:
So a torque unit is a force unit times a length unit. With 1 lbf = 4.4482216152605 N (exact) and 1 ft = 0.3048 m (exact), 1 lbf·ft = 1.3558179 N·m. The most used factors:
| From | To | Multiply by |
|---|---|---|
| lbf·ft | N·m | 1.355818 |
| N·m | lbf·ft | 0.737562 |
| lbf·in | N·m | 0.112985 |
| N·m | lbf·in | 8.850746 |
| kgf·m | N·m | 9.80665 |
| lbf·ft | lbf·in | 12 |
Power follows from torque and rotational speed:
Worked example
A wheel-nut spec in a European service manual reads 120 N·m, but your click wrench is marked in pound-feet.
120 × 0.737562 = 88.5 lbf·ft. Set the wrench to 88 or 89 lbf·ft.
Going the other way, a US spec of 100 lbf·ft is 100 × 1.355818 = 135.6 N·m.
A small spark plug spec of 25 N·m is 25 × 8.850746 = 221 lbf·in, or 18.4 lbf·ft.
Power check. An engine making 100 lbf·ft at 5,252 rpm produces 100 × 5,252 ÷ 5,252 = 100 hp (74.6 kW). An electric motor producing 400 N·m at 3,000 rpm delivers 400 × 2π × 3,000 ÷ 60 = 125.7 kW, about 168.5 hp.
Torque in practice
- Fasteners. A torque spec sets bolt clamping force indirectly. Friction eats most of the applied torque, so manuals specify whether threads should be dry, oiled or treated with thread locker; lubricated threads reach the same clamp load at a lower torque.
- Units on tools. Small screwdrivers and bicycle tools are often scaled in N·m or lbf·in; ½-inch drive wrenches in lbf·ft. Always confirm the unit printed on the scale before setting it.
- Engines and motors. Peak torque tells you how hard an engine pulls; power (torque × speed) tells you how fast it can do work. Electric motors make near-full torque from standstill, which is why EVs feel quick off the line.
Torque is not energy
The newton meter is dimensionally the same as the joule, but torque and energy are different quantities. Torque is a twisting effort that exists even when nothing moves; energy (work) is force times the distance actually moved. When torque rotates something through an angle θ in radians, the work done is τ × θ — that is the bridge between the two, and it is how the power formula above arises.
For straight-line forces, use the force converter; for power figures, the power converter or horsepower to kilowatts. To compute work from force and distance, see the work calculator.
Frequently asked questions
How many N·m is one foot-pound of torque?
One pound-force foot is 1.3558 N·m (1.355817948 to ten significant digits). It comes from 1 lbf = 4.4482216 N acting on a 0.3048 m lever.
How do I convert inch-pounds to foot-pounds?
Divide by 12, because a foot is 12 inches. A 300 in-lb spec is 25 lb-ft. Multiply by 12 to go back. Mixing the two is a classic way to over-tighten small bolts twelvefold.
Are foot-pounds and pound-feet the same?
Both names are used for the same torque unit, 1 pound-force acting at 1 foot. Engineers often prefer pound-foot (lbf·ft) for torque and keep foot-pound for work and energy, but wrench scales and repair manuals use them interchangeably.
Why does horsepower equal torque at 5,252 rpm?
Power in horsepower equals lbf·ft × rpm ÷ 5,252, because 1 hp is 33,000 ft·lbf per minute and one revolution is 2π radians (33,000 ÷ 2π ≈ 5,252). At exactly that speed the two numbers match, which is why torque and horsepower curves cross there on a dyno chart.