Torque Units: Newton-Meters, Pound-Feet, and Pound-Inches for Wheels, Bolts, and Bikes
October 21, 2026
Torque is a twisting force: the product of a force and the distance from the pivot at which it acts. A 100-newton force applied at the end of a 0.5-meter wrench produces 50 newton-meters (N·m). In customary units, 100 pounds at 1 foot gives 100 pound-feet (lb·ft). The conversions: 1 lb·ft = 1.3558 N·m, and 1 N·m = 0.73756 lb·ft. Pound-inches (lb·in) are one-twelfth of a pound-foot.
Fastener specifications are given in one or both systems, and getting them right matters for safety and for avoiding damage. A typical car lug nut spec of 100 lb·ft equals 135.6 N·m.
Skip the math and get your answer instantly:
Open the Weight Converter →Conversion Factors
To convert lb·ft to N·m, multiply by 1.3558. To convert N·m to lb·ft, multiply by 0.7376. For lb·in to N·m, multiply by 0.11298. For kilogram-force meters (kgf·m), used in some older specs, multiply by 9.80665 to get N·m. Be careful with units: a spec of 80 'Nm' and 80 'lb·ft' differ by 36%. Also note that torque (energy per angle) has the same dimensions as energy, but it is a different quantity; the SI unit for energy is the joule, so use N·m for torque to avoid confusion.
| Application | Typical torque (N·m) | Typical torque (lb·ft) |
|---|---|---|
| Bicycle stem bolt | 5 to 8 | 3.7 to 5.9 |
| Bicycle crank bolt | 40 to 54 | 30 to 40 |
| Spark plug | 20 to 30 | 15 to 22 |
| Car lug nut | 100 to 140 | 74 to 103 |
| Oil drain plug | 25 to 40 | 18 to 30 |
| Cylinder head bolt | 60 to 100 plus angle | 44 to 74 plus angle |
| Large truck lug nut | 400 to 600 | 295 to 440 |
Using a Torque Wrench
A click-type torque wrench is set to the target value and clicks or gives a slight give when the torque is reached. Stop pulling at the click; do not keep tightening. Pull smoothly and at the end of the handle, since the wrench is calibrated for the specified lever arm. Store it at its lowest setting (not zero) to preserve spring calibration, and have it checked periodically. Tighten fasteners in the sequence and stages specified, such as a star pattern for wheels, to seat parts evenly.
Torque specs assume clean, dry threads unless specified otherwise. Lubrication changes the friction and can make the actual clamping force much higher than intended, up to 25% to 40% more, so do not add oil to threads unless the manual says so.
Why the Right Torque Matters
Under-tightening leaves fasteners loose and can cause vibration failures, leaks, or wheels coming off. Over-tightening can stretch bolts, strip threads, crack parts such as aluminum components and carbon bike frames, and damage gaskets. For carbon fiber parts, manufacturers specify low torque (often 4 to 6 N·m) and sometimes recommend carbon assembly paste. For wheel lug nuts, re-check after the first 50 to 100 miles when fitting new wheels.
Power, Torque, and Angular Units
Torque is related to power: power in watts = torque in N·m × angular speed in rad/s. An engine delivering 300 N·m at 3,000 rpm (314 rad/s) produces 94 kW, about 126 hp. In customary units, horsepower = torque in lb·ft × rpm ÷ 5,252. These relationships link what you feel in acceleration (torque) to the power output.
Handy Rules
A rough way to estimate: 1 lb·ft is about 1.36 N·m, or 'a third more'. 100 N·m is about 74 lb·ft. For a quick check, a 10-inch wrench (0.25 m) with 20 kg of force (196 N) at the end applies about 49 N·m. Use proper tools, since a cheater bar can multiply torque unexpectedly.
Frequently Asked Questions
How many N·m is 100 lb·ft?
About 135.6 N·m.
How do I convert N·m to lb·ft?
Multiply by 0.7376.
What torque should I use for car lug nuts?
Check your manual. Typical values are 80 to 100 lb·ft (110 to 140 N·m).
Should I lubricate threads before torquing?
Only if the specification says so. Lubricant changes the clamping force for a given torque.
What's the difference between torque and horsepower?
Torque is twisting force. Power is the rate of doing work, equal to torque times rotational speed.