ft-lb to Nm (Foot-pounds → Newton-meters)
1. Core Idea
ft-lb and Nm are the same kind of quantity (torque/work) in different systems. 1 ft-lb = 1.355818 Nm. Multiply by 1.355818 to get Nm; divide (or ×0.737562) to go back.
2. Formula
Main: Nm = ft-lb × 1.355818
Reverse: ft-lb = Nm ÷ 1.355818 (≈ Nm × 0.737562)
Factor comes from exact foot (0.3048 m) and pound‑force (4.448221615 N).
3. Quick Values
- 1 ft-lb → 1.356 Nm
- 5 ft-lb → 6.780 Nm
- 10 ft-lb → 13.56 Nm
- 25 ft-lb → 33.90 Nm
- 50 ft-lb → 67.79 Nm
- 75 ft-lb → 101.69 Nm
- 100 ft-lb → 135.58 Nm
- 300 ft-lb → 406.75 Nm
4. 3-Step Example
Example: 120 ft-lb → ? Nm
- Formula: Nm = ft-lb × 1.355818
- Plug in: 120 × 1.355818
- Answer: 162.698 ≈ 162.70 Nm
5. Where It’s Used
Torque specs (wheels, engines), assembly, fasteners, tool calibration, cross‑system documentation.
6. Accuracy & Tips
- Full precision: 1.355818; mental: 1.356.
- Round to spec granularity (0.1 Nm or whole ft-lb).
- Many wrenches dual‑scale—no manual conversion needed.
- Nm numerically equals J, but context is torque.
7. More Examples
| ft-lb | Nm |
|---|---|
| 8 | 10.8465 |
| 18 | 24.4047 |
| 42 | 56.9436 |
| 180 | 244.047 |
8. FAQ
Is ft-lb the same as lb-ft?
Yes—just reversed order. Pick one style and stay consistent.
Does 1 N·m always equal 1 J?
Numerically yes; context differs (torque vs energy).