# Torque converter (N·m, lb-ft)

> Convert N·m to lb-ft, lb-ft to N·m, lb-in and kgf·m for torque wrench and bolt specifications, using 1 lbf·ft = 1.3558179483314004 N·m exactly.

Interactive version: https://www.calcopenly.com/conversion/torque-converter
Subject: Unit converters

Torque is force times lever length, so every torque unit is a force unit multiplied by a length unit, held here as newton-metres. One pound-foot is 4.4482216152605 N × 0.3048 m = 1.3558179483314004 N·m exactly, a pound-inch is a twelfth of that, and a kilogram-force metre is 9.80665 N·m.

The default converts 100 N·m to 73.756 lbf·ft, the scale of wheel-nut and engine torque figures. Bicycle parts and small fasteners use smaller values: 5 N·m is 44.25 lbf·in.

Torque and energy share the dimension N·m, but NIST SP 811 specifies the newton metre, not the joule, as the unit of moment of force, so a torque is never written in joules.

## Inputs

- **Value**: A number in the “from” unit, or with its own unit
- **From** (options: newton-metre (N·m), kilonewton-metre (kN·m), pound-foot (lbf·ft), pound-inch (lbf·in), kilogram-force metre (kgf·m))
- **To** (options: newton-metre (N·m), kilonewton-metre (kN·m), pound-foot (lbf·ft), pound-inch (lbf·in), kilogram-force metre (kgf·m))

## Results

- Converted value — main result
- Conversion
- Conversion factor
- Exactness

## Formula

$$
\begin{gathered} x_{\text{to}} = x_{\text{from}} \times \dfrac{f_{\text{from}}}{f_{\text{to}}} \\ f = \text{one unit expressed in } \text{N·m} \end{gathered}
$$

## Worked examples

### 100 N·m in lbf·ft

- Value: 100 N·m
- From: newton-metre (N·m)
- To: pound-foot (lbf·ft)
- **Converted value: 73.7562149277 lbf·ft**
- Checked against: 100 / (4.4482216152605 × 0.3048) (Python 3.8 fractions from the legal definitions)

### 1 lbf·ft in N·m

- Value: 1 lbf·ft
- From: pound-foot (lbf·ft)
- To: newton-metre (N·m)
- **Converted value: 1.35581794833 N·m**
- **Exactness: Exact**
- Checked against: 4.4482216152605 N × 0.3048 m = 1.3558179483314004 N·m (NIST SP 811 App. B)

### 12 lbf·in is 1 lbf·ft

- Value: 12 lbf·in
- From: pound-inch (lbf·in)
- To: pound-foot (lbf·ft)
- **Converted value: 1 lbf·ft**
- Checked against: 12 in = 1 ft

### 1 kgf·m in N·m

- Value: 1 kgf·m
- From: kilogram-force metre (kgf·m)
- To: newton-metre (N·m)
- **Converted value: 9.80665 N·m**
- Checked against: 9.80665 N × 1 m

## Questions

### How do I convert N·m to lb-ft?

Multiply by 0.737562, or divide by 1.35582. 100 N·m is 73.76 lbf·ft, and a 120 N·m wheel-nut setting is 88.51 lbf·ft. The factor comes from 1 lbf·ft = 4.4482216152605 N × 0.3048 m, which is exact, so only the reverse direction is rounded.

### Is lb-ft the same as ft-lb?

They are the same size, 1.3558 N·m. By convention the pound-foot (lb-ft, lbf·ft) is used for torque and the foot-pound (ft-lb, ft·lbf) for work or energy, mirroring the SI split between N·m for torque and joules for energy. In everyday use “ft-lb” is often written for torque too, and the number is the same.

### How do I convert lb-in to N·m?

Multiply by 0.112985. A pound-inch is one twelfth of a pound-foot, so 12 lbf·in = 1 lbf·ft = 1.3558 N·m. Small fasteners are specified in lbf·in or N·m: 50 lbf·in is 5.65 N·m, and 5 N·m is 44.25 lbf·in.

### What is a kgf·m in N·m?

Exactly 9.80665 N·m, the torque of one kilogram-force on a 1 m lever. Older workshop manuals give torque in kgf·m, sometimes written kg·m or kgm, so a 10 kgf·m figure is 98.07 N·m or 72.33 lbf·ft.

### Why is torque not measured in joules?

Torque and energy are different quantities that happen to share the dimension N·m. NIST SP 811 states that the SI unit of moment of force is the newton metre rather than the joule. Energy is force times distance moved, torque is force times lever arm, and a torque of 1 N·m acting through one full turn does 2π J of work.

### How accurate is the torque converter?

Accuracy depends on your inputs and the method's assumptions. Decimal arithmetic uses 50 significant digits, but estimates, numerical methods and source data can be less precise; the displayed rounding does not remove those limits. It is checked against 4 worked examples whose answers come from independent sources; for example, “100 N·m in lbf·ft” is checked against 100 / (4.4482216152605 × 0.3048) (Python 3.8 fractions from the legal definitions).

### Where does the method come from?

NIST SP 811 (2008), Guide for the Use of the SI, Appendix B — conversion factors; NIST Handbook 44, Appendix C — General tables of units of measurement.

## Sources

- [NIST SP 811 (2008), Guide for the Use of the SI, Appendix B — conversion factors](https://www.nist.gov/pml/special-publication-811)
- [NIST Handbook 44, Appendix C — General tables of units of measurement](https://www.nist.gov/pml/owm/nist-handbook-44-current-edition)