What this calculator does
Torque specifications turn up in three units depending on where the equipment was designed. Inch-pounds are common for small fasteners and electronics, foot-pounds for automotive work in the US, and newton-metres almost everywhere else. Torque wrenches are usually calibrated in one or two of them, not all three.
The conversions are fixed and exact, since the pound-force, the inch and the newton are all defined quantities. This converter shows all three units at once so a specification in any of them can be matched to whichever scale the wrench actually has.
The formula
Convert the entered value to newton-metres using its factor, then out to the other two. One inch-pound is 0.112984829 newton-metres, and one foot-pound is exactly twelve times that, at 1.355817948 newton-metres.
| Term | Meaning |
|---|---|
| Inch-pound (lbf·in) | A pound-force applied at a distance of one inch. Used for small fasteners where foot-pounds would be an awkwardly small number. |
| Foot-pound (lbf·ft) | A pound-force applied at one foot. Exactly twelve inch-pounds. |
| Newton-metre (N·m) | The SI unit of torque: one newton applied at one metre. |
The inputs explained
| Field | What to enter |
|---|---|
| Value | The torque value to convert. |
| From unit | The unit the value is currently in. The other two are calculated from it. |
When to use it
Following a torque specification
A manual quoting inch-pounds and a wrench reading newton-metres need converting between them before anything is tightened, since over-torquing a small fastener is easy and hard to undo.
Working on imported equipment
Machinery designed in one region and serviced in another routinely mixes units across the manual, the fasteners and the tools.
Checking a low-range wrench
Small assemblies are often specified in inch-pounds precisely because the foot-pound figure would be a fraction, and converting confirms the specification sits within the wrench range.
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 do common inch-pound figures convert to?
A range of inch-pound torque values in the other two units.
| Inch-pounds | Newton-metres | Foot-pounds |
|---|---|---|
| 10 lbf·in | 1.130 N·m | 0.833 lbf·ft |
| 25 lbf·in | 2.825 N·m | 2.083 lbf·ft |
| 50 lbf·in | 5.649 N·m | 4.167 lbf·ft |
| 100 lbf·in | 11.298 N·m | 8.333 lbf·ft |
| 200 lbf·in | 22.597 N·m | 16.667 lbf·ft |
Questions
Why are there twelve inch-pounds in a foot-pound?
Because there are twelve inches in a foot, and torque is force multiplied by distance. The same force applied twelve times further out produces twelve times the torque.
Is a newton-metre the same as a joule?
Dimensionally they are the same, but they describe different things. A joule is energy transferred; a newton-metre as torque is a rotational force that need not move anything. The convention is to keep the two names separate to avoid confusing the concepts.
What about kilogram-force metres?
Some older equipment is specified in kgf·m, which is about 9.807 newton-metres. It is a different unit again and should not be read as newton-metres, since the gap is nearly a factor of ten.
Does the conversion depend on the fastener?
No. The unit conversion is fixed arithmetic. What varies by fastener is the correct torque value itself, which comes from the manufacturer specification rather than from any calculation here.
For the force behind the torque, see the pound-force to newtons converter. For bolt tightening from a friction factor, see the bolt torque calculator.