ft-lbs to Nm Converter (Foot-Pounds to Newton-Meters)
Convert torque in foot-pounds to newton-meters for metric torque wrenches and service manuals. 1 lbf·ft = 1.35582 N·m, so 80 ft-lbs is 108.47 N·m and 100 ft-lbs is 135.58 N·m.
Real-World Benchmarks
Multi-Unit Conversion Matrix
| Group | Measurement | Symbol | Equivalent Value |
|---|---|---|---|
| SI & Metric | Newton-Millimeter | N·mm | 108,465.4359 |
| SI & Metric | Newton-Centimeter | N·cm | 10,846.5436 |
| SI & Metric | Newton-Meter | N·m | 108.4654 |
| SI & Metric | Kilonewton-Meter | kN·m | 0.1085 |
| Imperial & US Customary | Pound-Foot | lbf·ft | 80 |
| Imperial & US Customary | Pound-Inch | lbf·in | 960 |
| Imperial & US Customary | Ounce-Inch | ozf·in | 15,360 |
| Kilogram-force | Kilogram-Force Meter | kgf·m | 11.0604 |
| Kilogram-force | Kilogram-Force Centimeter | kgf·cm | 1,106.0396 |
Step-by-Step Mathematical Explanation
- 1 lbf·ft equals 1.35581794833 N·m, so multiply: 80 × 1.35581794833 = 108.465436 N·m.
- Direct factor: 1 lbf·ft = 1.35581795 N·m.
Essential Conversion Factors
Pound-Foot: US engine torque and lug nuts (ft-lb)
lbf·ft to N·m formula
Direct Answer: 1 lbf·ft = 1.3558179 N·m, so multiply by 1.3558179: N·m = lbf·ft × 1.3558179. Going back: lbf·ft = N·m × 0.73756215.
How to convert pound-feet to newton-meters
A foot-pound of torque is one pound-force (4.4482216 N) acting at one foot (0.3048 m), which is 1.3558179 N·m. Multiply foot-pounds by 1.35582 to get newton-meters. US specs are usually in ft-lbs (or in-lbs for small fasteners); European and Asian manuals use N·m.
1. lbf·ft → N·m
Multiply the number of pound-feet by the conversion factor:
Example: 80 lbf·ft × 1.3558179 = 108.47 N·m.
2. N·m → lbf·ft
To go back, divide by the same factor, or multiply by its reciprocal, 0.73756215:
Example: 108.47 N·m ÷ 1.3558179 = 80 lbf·ft.
Mental math: add a third
Add a third of the ft-lbs value. The estimate is under 2% low:
90 ft-lbs: 90 + 30 = 120 N·m (exact: 122.02 N·m).
1 lbf·ft in other torque units
| Unit | 1 lbf·ft equals | Typical use |
|---|---|---|
| Newton-Millimeter | 1,355.8179 N·mm | Small fasteners and electronics |
| Newton-Centimeter | 135.58179 N·cm | Screwdrivers and small motors |
| Newton-Meter | 1.3558179 N·m | SI unit of torque — wrenches and engines |
| Kilonewton-Meter | 0.0013558179 kN·m | Structural and heavy machinery |
| Pound-Inch | 12 lbf·in | Small bolts and bicycle components (in-lb) |
| Ounce-Inch | 192 ozf·in | Servos and stepper motors |
| Kilogram-Force Meter | 0.13825495 kgf·m | Older Asian and European specs |
| Kilogram-Force Centimeter | 13.825495 kgf·cm | RC servos and small motors |
lbf·ft to N·m chart
| lbf·ft | N·m |
|---|---|
| 5 | 6.78 |
| 10 | 13.56 |
| 15 | 20.34 |
| 18 | 24.4 |
| 20 | 27.12 |
| 25 | 33.9 |
| 30 | 40.67 |
| 35 | 47.45 |
| 40 | 54.23 |
| 45 | 61.01 |
| 50 | 67.79 |
| 55 | 74.57 |
| 60 | 81.35 |
| 65 | 88.13 |
| 70 | 94.91 |
| 75 | 101.69 |
| 80 | 108.47 |
| 85 | 115.24 |
| 90 | 122.02 |
| 100 | 135.58 |
| 110 | 149.14 |
| 120 | 162.7 |
| 140 | 189.81 |
| 150 | 203.37 |
| 200 | 271.16 |
| 250 | 338.95 |
| 300 | 406.75 |
| 400 | 542.33 |
| 500 | 677.91 |
N·m to lbf·ft chart
| N·m | lbf·ft |
|---|---|
| 5 | 3.69 |
| 10 | 7.38 |
| 12 | 8.85 |
| 15 | 11.06 |
| 20 | 14.75 |
| 25 | 18.44 |
| 27 | 19.91 |
| 30 | 22.13 |
| 35 | 25.81 |
| 40 | 29.5 |
| 45 | 33.19 |
| 50 | 36.88 |
| 55 | 40.57 |
| 60 | 44.25 |
| 70 | 51.63 |
| 80 | 59 |
| 90 | 66.38 |
| 100 | 73.76 |
| 110 | 81.13 |
| 120 | 88.51 |
| 130 | 95.88 |
| 140 | 103.26 |
| 150 | 110.63 |
| 180 | 132.76 |
| 200 | 147.51 |
| 250 | 184.39 |
| 300 | 221.27 |
| 350 | 258.15 |
| 400 | 295.02 |
| 450 | 331.9 |
| 500 | 368.78 |
| 600 | 442.54 |
| 800 | 590.05 |
| 1,000 | 737.56 |
Frequently Asked Questions
What is 100 lbf·ft in N·m?
100 lbf·ft is 135.58 N·m (100 × 1.3558179).
What is 250 lbf·ft in N·m?
250 lbf·ft is 338.95 N·m (250 × 1.3558179).
How many Nm is 1 ft-lb?
One foot-pound is 1.35582 N·m (1.3558179 to eight figures).
How do I convert inch-pounds to Nm?
Divide inch-pounds by 12 to get foot-pounds, or multiply by 0.112985 to get N·m directly. 100 in-lbs = 11.30 N·m. The torque converter above includes lbf·in.