What this calculator does
Torque is a force applied at a distance from a pivot, so every unit is a force unit paired with a length unit. The newton metre is the SI form. Pound-feet come from the imperial pound-force and foot, and kilogram-force metres from an older metric convention that used weight rather than force.
The unit to watch is the pound-inch, which is a twelfth of a pound-foot. Small fasteners and electronics are often specified in pound-inches, and reading one as a pound-foot overtightens by a factor of twelve, which is more than enough to strip a thread.
The formula
Every unit has a fixed factor in newton metres and the conversion multiplies to reach that base then divides to leave it. A pound-foot is 1.355818 Nm, derived from the pound-force and the foot. A kilogram-force metre is 9.80665 Nm, which is standard gravity in disguise, since a kilogram-force is the weight of a kilogram under it.
| Term | Meaning |
|---|---|
| Newton metre (Nm) | The SI unit: one newton acting one metre from the pivot. |
| Pound-foot (lbf·ft) | One pound-force at one foot, about 1.356 Nm. Often written lb-ft or ft-lb. |
| Pound-inch (lbf·in) | A twelfth of a pound-foot, about 0.113 Nm. Used for small fasteners. |
| Kilogram-force metre (kgf·m) | About 9.807 Nm, from the older metric system that measured force as weight. |
The inputs explained
| Field | What to enter |
|---|---|
| Value | The torque value to convert. |
| From | The unit it is currently in. Check carefully whether a specification says pound-feet or pound-inches. |
| To | The unit you want the answer in. |
When to use it
Setting a torque wrench
Wrenches are calibrated in one unit and specifications are written in another, most often Nm against pound-feet. Converting before setting the wrench is the whole point of the exercise.
Reading an engine specification
Engine torque appears in Nm, pound-feet or kgf·m depending on the market, and the three numbers for one engine look nothing alike.
Working on small fasteners
Electronics, optics and bicycle components are usually specified in pound-inches or in newton metres below 10. Getting the unit wrong here is how threads get stripped.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
What is one of each torque unit in newton metres?
A single unit of each kind, converted to newton metres to compare their scale.
| From | In newton metres |
|---|---|
| Kilonewton metre | 1,000 Nm |
| Pound-foot | 1.355818 Nm |
| Pound-inch | 0.1129848 Nm |
| Kilogram-force metre | 9.80665 Nm |
| Ounce-inch | 0.00706155 Nm |
Converting 50 Nm to the other torque units
A torque of 50 newton metres expressed in each of the other units.
| To | Result |
|---|---|
| Pound-feet | 36.87810606 lbf_ft |
| Pound-inches | 442.5374033 lbf_in |
| Kilogram-force metres | 5.09858107 kgf_m |
| Kilonewton metres | 0.05 kNm |
Questions
Is lb-ft the same as ft-lb?
For torque, yes, and both are in common use. Strictly the force should come first, making lbf·ft correct, but ft-lb is written just as often and means the same thing. Where the order genuinely matters is in distinguishing torque from energy, since a foot-pound of work is a different quantity that happens to share the units.
How many Nm in a pound-foot?
About 1.3558. Going the other way, one newton metre is about 0.7376 pound-feet. A useful rough check is that a newton metre is roughly three quarters of a pound-foot.
What is the difference between pound-feet and pound-inches?
A factor of twelve, since there are twelve inches in a foot. 10 pound-feet is 120 pound-inches. Small fasteners are specified in pound-inches precisely so the number is not an awkward fraction, and treating one as the other overtightens badly.
Why does kilogram-force metre involve gravity?
Because a kilogram-force is defined as the weight of one kilogram under standard gravity, 9.80665 m/s². It is a force unit built from a mass unit, which is why the conversion carries that constant. The unit is largely obsolete but still appears on older equipment and in some Japanese and European specifications.
For force and pressure rather than torque, see the pressure converter. For power, which torque produces when combined with rotational speed, see the power converter.