What do Nm and ft-lbs measure?
Newton-meters (N·m) and foot-pounds (ft-lb) are both units of torque — also called the moment of force or rotational force. Torque measures the tendency of a force to rotate an object around a fixed point (the pivot point). The formula is:
Torque = Force × Distance from pivot
- N·m (Newton-meter) — the SI unit of torque. Used in the metric system worldwide.
- ft-lb (foot-pound) — the US customary unit. Used in the FPS (foot-pound-second) system, common in the USA and UK.
💡 Note: foot-pounds (ft-lb) is a unit of torque, while foot-pounds-force may refer to energy. They share the same symbol but represent different physical quantities in different contexts.
How to convert Newton-meters to foot-pounds?
The conversion from N·m to ft-lb is straightforward:
1 N·m = 0.7376 ft-lb
Or more precisely: 1 N·m = 0.73756215 ft-lb
To convert any value from N·m to ft-lb, multiply by 0.7376:
ft-lb = N·m × 0.7376
How to convert ft-lbs to Nm?
To convert foot-pounds back to Newton-meters, multiply by 1.3558:
N·m = ft-lb × 1.3558
Nm to ft-lbs Conversion Table
| N·m | ft-lb | N·m | ft-lb |
|---|---|---|---|
| 1 | 0.738 | 50 | 36.88 |
| 2 | 1.475 | 75 | 55.32 |
| 5 | 3.688 | 100 | 73.76 |
| 10 | 7.376 | 150 | 110.6 |
| 20 | 14.75 | 200 | 147.5 |
| 25 | 18.44 | 250 | 184.4 |
| 30 | 22.13 | 300 | 221.3 |
| 40 | 29.50 | 400 | 295.0 |
Torque conversion calculator: example of use
Suppose your car's engine specifications say the torque is 250 N·m, and you want to know what that is in ft-lb:
250 × 0.7376 = 184.4 ft-lb
Another example: a bolt torque specification says 80 ft-lb. To find the equivalent in N·m:
80 × 1.3558 = 108.5 N·m
Metric vs. American Measurement Systems
| System | Unit | Symbol | Notes |
|---|---|---|---|
| Metric / SI | Newton-meter | N·m | Standard SI unit of torque |
| Kilogram-force meter | kgf·m | 1 kgf·m = 9.8067 N·m | |
| Kilogram-force centimeter | kgf·cm | 1 kgf·cm = 0.09807 N·m | |
| US / American | Foot-pound | ft-lb | Standard US unit; 1 ft-lb = 1.3558 N·m |
| Inch-pound | in-lb | 1 in-lb = 0.1130 N·m (1/12 of ft-lb) | |
| Physics | Joule per radian | J/rad | Equivalent to N·m (1 J/rad = 1 N·m) |
Other units of torque: kgf-cm to Nm, J/rad to Nm, and kgm to Nm
kgf·cm to N·m
The kilogram-force centimeter is widely used in older engineering documents and in some industries:
1 kgf·cm = 0.0980665 N·m
Or: N·m = kgf·cm × 0.0980665
| kgf·cm | N·m |
|---|---|
| 1 | 0.0981 |
| 10 | 0.981 |
| 100 | 9.807 |
| 1000 | 98.07 |
J/rad to N·m
The joule per radian (J/rad) is dimensionally equivalent to the Newton-meter. Both represent the same physical quantity:
1 J/rad = 1 N·m
This equivalence comes from the definition of torque as energy per angle: when a torque of 1 N·m acts through an angle of 1 radian, it does 1 joule of work.
kgm (kgf·m) to N·m
The kilogram-force meter (often written as "kgm" informally) is a common metric unit in older references and some European engineering standards:
1 kgf·m = 9.80665 N·m
Or: N·m = kgf·m × 9.80665
| kgf·m | N·m | ft-lb |
|---|---|---|
| 1 | 9.807 | 7.233 |
| 5 | 49.03 | 36.17 |
| 10 | 98.07 | 72.33 |
| 20 | 196.1 | 144.7 |
⚠️ Note: the "kgf" prefix is important — it denotes kilogram-force, not just kilogram (mass). The standard gravity (g = 9.80665 m/s²) defines the conversion factor.
FAQs
How many foot-pounds is 100 Nm?
100 N·m × 0.7376 = 73.76 ft-lb
How many Nm is 100 ft-lbs?
100 ft-lb × 1.3558 = 135.6 N·m
Is 1 Nm the same as 1 J/rad?
Yes. They are dimensionally identical: 1 N·m = 1 J/rad. Both equal one joule of work done per radian of rotation.
What is the difference between Nm and kgm?
N·m uses the SI unit of force (Newton), while kgf·m uses the kilogram-force. Since 1 kgf = 9.80665 N, one kgf·m equals 9.80665 N·m.
Is ft-lbs the same as lbf-ft?
Yes, foot-pounds (ft-lb) and pound-force feet (lbf·ft) refer to the same unit of torque. Both equal 1.3558 N·m.
Where are torque units commonly used?
- Automotive: engine torque specs (N·m in Europe, ft-lb in the USA)
- Mechanical engineering: bolt torque specifications
- Bicycle / sports equipment: component tightening torques (usually N·m)
- Electrical motors: rated torque output