Torque Converter
Convert torque between newton metres, kilogram-force metres and pound-force feet.
Written by Rahman · Last reviewed
Quick answer
Torque conversion runs through the newton metre. One pound-force foot is 1.3558 N·m, one pound-force inch is 0.113 N·m and one kilogram-force metre is 9.80665 N·m. Torque wrenches are calibrated in either lbf·ft or N·m, and confusing the two (a factor of about 1.36) is a common cause of over-tightening.
| Newton metre (N·m) | 1 |
| Newton centimetre (N·cm) | 100 |
| Newton millimetre (N·mm) | 1000 |
| Kilonewton metre (kN·m) | 0.001 |
| Kilogram-force metre (kgf·m) | 0.1019716213 |
| Gram-force centimetre (gf·cm) | 10197.16213 |
| Pound-force foot (lbf·ft) | 0.7375621484 |
| Pound-force inch (lbf·in) | 8.850745793 |
| Ounce-force inch (ozf·in) | 141.6119329 |
About the Torque Converter
Torque is the rotational force that turns an object around an axis: for example, the force a wrench applies to a bolt or an engine to a crankshaft. The SI unit is the newton metre.
This converter handles newton metres, kilogram-force metres and pound-force feet, the figures most often quoted for engines and fasteners.
Torque and energy share a unit but are not the same thing
A newton metre is force multiplied by distance, and so is a joule. Dimensionally they are identical, yet torque is never expressed in joules and energy is never expressed in newton metres, because the two describe different physical situations.
The difference is direction. In energy, the force acts along the distance it moves through. In torque, the force acts perpendicular to the lever arm, producing rotation rather than displacement. Keeping the units visually distinct is a convention that exists precisely to stop the two being added together.
- Torque multiplied by angular displacement gives energy; torque multiplied by rotational speed gives power.
- An engine's torque figure and its power figure describe different things: torque is turning effort, power is the rate of doing work.
- Pound-force feet and foot-pounds are frequently used interchangeably in writing, though strictly the former is torque and the latter energy.
Reading a fastener specification correctly
Bolt torque specifications are among the most common reasons to convert on this page, and they carry two traps. The first is the difference between pound-force feet and pound-force inches: a factor of twelve, and both are abbreviated in ways that are easy to misread on a small label.
A specification of 90 N·m is about 66.4 lbf·ft. Read as pound-force inches instead, the same figure would be twelve times too small, enough to leave a critical fastener barely finger-tight.
- Kilogram-force metres appear in older and some Asian specifications; one is 9.80665 N·m.
- Small fasteners and electronics are usually specified in pound-force inches or newton centimetres, larger assemblies in pound-force feet or newton metres.
- Torque specifications assume specific conditions: clean, dry or lubricated threads as stated. Lubrication changes the clamping force a given torque produces.
Frequently Asked Questions
How do I convert newton metres to pound-force feet?
⌄
Multiply newton metres by about 0.73756 to get pound-force feet.
What is engine torque?
⌄
Engine torque is the rotational force an engine produces. Along with engine speed, it determines the engine’s power output.
Why is correct torque important for bolts?
⌄
Tightening a bolt to the specified torque ensures it is secure without being over-stressed, which could cause it to fail.