# Conversor de par (N·m, lb-ft)

> Convierta N·m a lb-ft, lb-ft a N·m, lb-in y kgf·m para llaves dinamométricas y pernos, usando exactamente 1 lbf·ft = 1.3558179483314004 N·m.

Versión interactiva: https://www.calcopenly.com/es/conversion/torque-converter
Tema: Conversores de unidades

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.

## Datos

- **Valor**: Un número en la unidad de origen, o acompañado de su propia unidad
- **De** (opciones: newton-metre (N·m), kilonewton-metre (kN·m), pound-foot (lbf·ft), pound-inch (lbf·in), kilogram-force metre (kgf·m))
- **A** (opciones: newton-metre (N·m), kilonewton-metre (kN·m), pound-foot (lbf·ft), pound-inch (lbf·in), kilogram-force metre (kgf·m))

## Resultados

- Valor convertido — resultado principal
- Conversión
- Factor de conversión
- Exactitud

## Fórmula

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

## Ejemplos resueltos

### 100 N·m in lbf·ft

- Valor: 100 N·m
- De: newton-metre (N·m)
- A: pound-foot (lbf·ft)
- **Valor convertido: 73.7562149277 lbf·ft**
- Fuente de comprobación: 100 / (4.4482216152605 × 0.3048) (Python 3.8 fractions from the legal definitions)

### 1 lbf·ft in N·m

- Valor: 1 lbf·ft
- De: pound-foot (lbf·ft)
- A: newton-metre (N·m)
- **Valor convertido: 1.35581794833 N·m**
- **Exactitud: Exacto**
- Fuente de comprobación: 4.4482216152605 N × 0.3048 m = 1.3558179483314004 N·m (NIST SP 811 App. B)

### 12 lbf·in is 1 lbf·ft

- Valor: 12 lbf·in
- De: pound-inch (lbf·in)
- A: pound-foot (lbf·ft)
- **Valor convertido: 1 lbf·ft**
- Fuente de comprobación: 12 in = 1 ft

### 1 kgf·m in N·m

- Valor: 1 kgf·m
- De: kilogram-force metre (kgf·m)
- A: newton-metre (N·m)
- **Valor convertido: 9.80665 N·m**
- Fuente de comprobación: 9.80665 N × 1 m

## Preguntas

### 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.

### ¿Qué precisión tiene «Conversor de par (N·m, lb-ft)»?

La precisión depende de tus datos y de los supuestos del método. El cálculo decimal usa 50 cifras significativas, pero las estimaciones, los métodos numéricos y los datos de origen pueden ser menos precisos; el redondeo mostrado no elimina esos límites. Ejemplos resueltos comprobados con fuentes independientes: 4. Por ejemplo, «100 N·m in lbf·ft» se comprueba con 100 / (4.4482216152605 × 0.3048) (Python 3.8 fractions from the legal definitions).

### ¿De dónde procede el método?

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.

## Fuentes

- [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)